Fluid flow measurement and control

ABSTRACT

In accordance with one embodiment, a controller in a fluid delivery system controls magnitudes of pressure in a first volume and a second volume. The first volume is of a known magnitude. The second volume is of an unknown magnitude and varies. The controller estimates a temperature of gas in the first volume and a temperature of gas in the second volume based on measurements of pressure in the first volume and measurements of pressure in the second volume. The controller then calculates a magnitude of the second volume based on measured pressures of the gases and estimated temperatures of gases in the first volume and the second volume.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/171,433 (Attorney's docket number FLU12-15A) entitled “FLUIDFLOW MEASUREMENT AND CONTROL,” filed on Feb. 3, 2014, the entireteachings of which are incorporated herein by this reference.

U.S. patent application Ser. No. 14/171,433 claims the benefit of U.S.Provisional Patent Application Ser. No. 61/761,109 (Attorney's docketnumber FLU12-15p) entitled “Measurement and Control of Fluid Flow in anIntravenous Pump,” filed on Feb. 5, 2013, the entire teachings of whichare incorporated herein by this reference.

BACKGROUND

Conventional techniques of delivering fluid to a recipient can includedrawing a fluid from a fluid source into a chamber of a diaphragm pump.After the chamber is filled, a respective fluid delivery system appliesa pressure to the chamber causing the fluid in the chamber to bedelivered to a corresponding patient. The rate at which the fluid isdelivered to the recipient may vary depending upon the magnitude ofpressure applied to the chamber.

Eventually, after applying pressure to the chamber for a sufficientamount of time, all of the fluid in the chamber is delivered to therecipient.

In most applications, the amount of fluid drawn into the chamber of thediaphragm pump is substantially less than the amount of fluid to bedelivered to the patient in total. To deliver the appropriate amount offluid to the patient over time, the fluid delivery system repeats thecycle of drawing fluid from the fluid source into the chamber, and thenapplying pressure to the chamber to deliver the fluid to the recipient.

According to conventional techniques, based on the amount of elapsedtime between time successive operations of drawing fluid into andexpelling the fluid out of the chamber in the diaphragm pump, the fluiddelivery system is able to determine the rate at which fluid isdelivered to a corresponding patient.

BRIEF DESCRIPTION OF EMBODIMENTS

Embodiments herein are novel over conventional methods.

For example, in a general embodiment, to determine a fluid flow to arecipient, the fluid delivery system as described herein includes avalve disposed between a first volume (such as a chamber of knownvolume) and a second volume (such as a chamber of a diaphragm pump). Thecontroller of the fluid delivery system initially closes the valve toprevent a transfer of gas between the first volume and the secondvolume. While the valve is closed, the controller controls a pressure ofthe second volume to deliver fluid in the diaphragm pump to a recipient.During a measurement of determining a capacity of the second volume anda rate of flow of fluid to the recipient, the controller opens the valvebetween the first volume and the second volume to enable a transfer ofgas and to equalize the first volume and the second volume tosubstantially the same pressure. The controller calculates the magnitudeof the second volume based at least in part on measured pressures of thegases before and after opening the valve.

As further discussed below, embodiments herein include improvements withrespect to determining fluid flow rates. For example, as furtherdiscussed herein, embodiments herein include improvements such astemperature estimation, discontinuous pump operation, multiple pumpembodiments, etc.

Temperature Estimation and Control

More specifically, in accordance with first embodiments, a fluiddelivery system includes a first volume (such as a first chamber) and asecond volume (such as a second chamber). Assume that the first volumeis of a known magnitude and that the second volume is of an unknownmagnitude. In one embodiment, a controller in the fluid delivery systemcontrols magnitudes of pressures in the first volume and the secondvolume to deliver fluid to a corresponding recipient.

To produce a more accurate measurement of fluid delivered to arecipient, the controller estimates a temperature of gas in the firstvolume and a temperature of gas in the second volume. The controllerestimates the temperatures based on measurements of pressure in thefirst volume and measurements of pressure in the second volume. In otherwords, in one embodiment, the controller derives the estimated gastemperatures at least in part from the measurement of pressures in thefirst volume and the second volume.

In addition to estimating temperatures, the controller as describedherein can be configured to calculate a magnitude of the second volumebased on a combination of measured pressures and estimated temperaturesof the gases in the first volume and the second volume. Thermal effectsof the first volume and/or the second volume can have an impact oncalculated volume. In accordance with yet further embodiments, toestimate the temperature of gas in the first volume and the temperatureof gas in the second volume, the controller derives the estimatedtemperature of the gas in the first volume and the estimated temperatureof the gas in the second volume based at least in part on thermaleffects due to changes in pressure of the gases in the first volume andthe second volume.

Physical attributes of the first volume and the second volume can affectrespective actual and estimated gas temperatures of the gases. Inaccordance with further embodiments, when estimating the temperature ofgas in the first volume and the temperature of gas in the second volume,the controller can be configured to derive the temperature of the gas inthe first volume and the temperature of the gas in the second volumebased at least in part on an estimated transfer of heat between thegases and respective physical boundaries defining the first volume andthe second volume.

By further way of non-limiting example, note that the second volume (asdiscussed above) can be a first chamber in a diaphragm pump. Thediaphragm pump can include a second chamber disposed adjacent the firstchamber. A flexible membrane in the diaphragm pump defines a boundarybetween the first chamber and second chamber. The controller controls apressure applied to the first chamber (the second volume) to pump fluidin the second chamber to a target recipient. As described herein, thecontroller can apply negative pressure to the second volume to decreasea size of the second volume, drawing fluid into the second chamber ofthe diaphragm pump. The controller can apply positive pressure to thefirst chamber (second volume) to expel fluid from the second chamber ofthe diaphragm pump to a corresponding downstream recipient.

In accordance with still further embodiments, when the controllerapplies positive pressure to the second volume, the second volumechanges over time as a result of delivering the fluid to the recipient.When estimating the temperature of gas in the first volume and thetemperature of gas in the second volume, the controller can beconfigured to derive the temperature of the gas in the first volume andthe temperature of the gas in the second volume based at least in parton a calculated change in the second volume over time.

In further embodiments, the controller uses the calculated magnitude ofthe second volume (volume of the first chamber in the diaphragm pump) todetermine a flow rate of delivering fluid from the second chamber of thediaphragm pump to the target recipient.

Discontinuous Control Operation

In accordance with second embodiments, a controller in a fluid deliverysystem initiates drawing fluid into a chamber of a diaphragm pump.During a delivery phase, the controller applies positive pressure to thechamber. The applied positive pressure pumps the fluid in the chamber toa target recipient. At one or more times during the delivery phase, thecontroller temporarily discontinues or interrupts application of apressure to the chamber to calculate how much of the fluid in thechamber has been pumped to the target recipient.

More specifically, assume that the fluid delivery system first initiatesfilling a chamber in a diaphragm pump. The fluid delivery system exertspressure on the chamber to deliver a portion of the fluid in thediaphragm pump to a downstream recipient. The fluid delivery systemtemporarily discontinues application of pressure to the chamber. In oneembodiment, discontinuing application of the pressure includes reducinga pressure applied to the chamber. The reduced pressure causes pumpingof the fluid in the chamber to the recipient to slow down or stop for ashort amount of time. The time of the interruption of pressure may be soshort that it is unnoticeable or insignificant.

During such time of temporarily discontinuing application of a pressure,the fluid delivery system calculates the amount of the fluid remainingin the chamber of the diaphragm pump.

After calculating the amount of fluid remaining in the chamber, thefluid delivery system applies pressure to the chamber again,(potentially the same or substantially similar pressure applied prior tothe interruption) causing the fluid in the chamber to resume normaldelivery of fluid to the recipient. In other words, resumption ofapplying the pressure to the chamber causes the fluid in the chamber toflow again to the recipient.

In one embodiment, the fluid delivery system repeats this process ofdiscontinuing application of the pressure to the chamber to calculate anamount of fluid remaining in the chamber multiple times during adelivery phase. Multiple measurements enable the fluid delivery systemto accurately detect a rate of delivering fluid to a recipient overtime.

In yet further embodiments, as mentioned, the controller can beconfigured to apply a substantially constant pressure (before and aftera step of temporarily discontinuing application of pressure) to thechamber to evacuate the fluid from the chamber into a respective conduitthat conveys the fluid to the target recipient.

Using the calculated amount of fluid remaining in the chamber atdifferent times during the delivery phase, the controller can calculatea flow rate of delivering the fluid in the chamber to the targetrecipient.

In accordance with further embodiments, the controller can be configuredto compare the calculated flow rate to a desired flow rate such as a setpoint. In response to detecting that a difference between the calculatedflow rate and the desired flow rate is greater than a threshold value,the controller can be configured to adjust a flow rate of the fluid fromthe chamber to the target recipient to be nearer to the desired flowrate.

Note that the controller can modify any suitable control parameter toadjust a flow rate of the fluid if it is different than a respectivedesired set point. For example, in one embodiment, the controlleradjusts a magnitude of the pressure applied to the chamber during thedelivery phase to increase or decrease the fluid delivery rate.Additionally, or alternatively, the controller can be configured toadjust resistance of an in-line fluid flow resistor disposed between thechamber and the target recipient.

Discontinuing application of the drive pressure to the pump chamber caninclude controlling magnitudes of pressure in the pump chamber and asecond reference to be dissimilar. The reference chamber can be a volumeof known magnitude; the pump chamber can be a volume of unknownmagnitude. In other words, as mentioned, the pump chamber can representa varying volume, a magnitude of which varies as fluid is delivered to arecipient.

In further embodiments, the controller opens a valve between thereference chamber and the pump chamber to substantially equalize apressure of gas in the reference chamber and the pump chamber. To moreaccurately calculate a rate of fluid delivery, as previously discussed,the controller can be configured to estimate the temperature of gas inthe reference chamber and a temperature of gas in the pump chamber basedon a measured pressure in the reference chamber and measured pressure ofthe pump chamber. The controller calculates how much fluid remains inthe chamber based at least in part on measured pressures of the gasesand the estimated temperatures of the gases in the reference chamber andthe pump chamber.

Also, as previously mentioned, the controller can be configured tocalculate how much of the fluid has been pumped to the target recipientbased at least in part on how much of the fluid drawn into the pumpchamber remains in the chamber after applying positive pressure to thepump chamber.

Multiple-Pump Embodiments

Further embodiments herein provide additional novel and improved fluiddelivery over conventional techniques.

More specifically, in accordance with one or more additionalembodiments, a fluid delivery apparatus includes controller hardware, apneumatically (gas) driven diaphragm pump, a positive displacement fluidpump, and a fluid conduit (fluid tight pathway to convey fluid)extending between the diaphragm pump through the peristaltic fluid pumpto a recipient. The diaphragm pump can be configured to receive thefluid from a remotely located fluid source. Accordingly, embodimentsherein include a pressure controlled variable displacement pump (such asa diaphragm pump) feeding a force based variable positive displacementpump (such as a peristaltic fluid pump, rotary lobe pump, progressivecavity pump, rotary gear pump, piston pump, diaphragm pump, screw pump,gear pump, hydraulic pump, rotary vane pump, rope pump, flexibleimpeller pump, etc.). During operation of delivering fluid to adownstream recipient, the controller hardware initially draws fluid intoa chamber of the diaphragm pump through the application of negativepressure. Subsequent to filling the chamber, the controller hardwareapplies positive pressure to the chamber of the diaphragm pump to outputthe fluid in the chamber (of the diaphragm pump) downstream through thefluid conduit to the positive displacement pump.

In one embodiment, the positive displacement pump includes anelastically deformable conduit (or segment) driven by a respectiveperistaltic fluid pump. During application of the pressure to thediaphragm chamber and outputting the fluid in the chamber downstream tothe peristaltic fluid pump, the controller hardware activates theperistaltic fluid pump to pump force the fluid disposed in the segmentfrom the peristaltic fluid pump along the fluid conduit to thedownstream recipient. Accordingly, a diaphragm pump delivers fluid tothe elastically deformable conduit; the peristaltic fluid pump thenapplies a peristaltic pump element in a sweeping motion to deliver thefluid in the segment downstream to a recipient.

More specifically, in one embodiment, the peristaltic pump element is incontact with and occludes (and/or pinches) the elastically deformableconduit. Via the occlusion or pinching, the peristaltic pump elementblocks and controls a flow of the displacement of fluid from thediaphragm pump into the segment. Sweeping physical contact of theperistaltic pump element with respect to the elastically deformableconduit controllably conveys fluid in the elastically deformable conduitdownstream to the recipient. Accordingly, in one embodiment, theperistaltic pump element performs multiple operations including: i)restricting (or holding back) a flow of the fluid received upstream ofthe peristaltic pump element from the diaphragm pump into the segment(elastically deformable conduit) as well as ii) controlling delivery offluid in the segment (elastically deformable conduit) downstream of theperistaltic pump element to the recipient.

In accordance with further embodiments, a pressure of the fluid upstreamof the peristaltic pump element is different than a pressure of thefluid downstream of the peristaltic pump element. More specifically, inone embodiment, a pressure of the fluid in a first portion of the fluidconduit upstream of the peristaltic pump element between the peristalticpump element (that pinches, occludes, controls, etc., a flow of thefluid) and the diaphragm pump is greater than a pressure of the fluid ina second portion of the fluid conduit downstream of the peristaltic pumpelement.

In accordance with further embodiments, a pressure of the fluid in afirst portion of the fluid conduit upstream of the peristaltic pumpelement between the peristaltic pump element (that pinches a flow of thefluid) and the diaphragm pump is less than a pressure of the fluid in asecond portion of the fluid conduit downstream of the peristaltic pumpelement.

In accordance with another embodiment, the controller hardware of thefluid delivery apparatus as described herein is further operable to:measure a rate of fluid expelled from the chamber of the diaphragm pumpdownstream to the segment of fluid conduit. In one embodiment, thecontroller hardware uses a measured rate of expelled fluid from thechamber to control a rate of moving motion of the peristaltic pumpelement to regulate the delivery of the fluid to the recipient at adesired flow rate.

The flow rate of fluid through the diaphragm pump can be measured in anysuitable manner. For example, in one embodiment, the controller hardwareis further operable to: cyclically receive (draw), over each of multiplecycles, a quantum of the fluid from a disparately located fluid sourcecontainer into the chamber of the diaphragm pump at each of multiplefill times.

In one embodiment, the controller hardware applies a negative pressureto the chamber of the diaphragm pump to draw the fluid from the fluidsource container. If desired, the controller hardware can be configuredto draw the fluid from the fluid source container into the chamber ofthe diaphragm pump during a condition in which a peristaltic pumpelement of the peristaltic fluid pump is in physical contact with thesegment of fluid conduit and blocks the flow of the fluid received fromthe diaphragm pump through the segment. Thus, because the peristalticpump element blocks fluid flow, instead of drawing fluid from theelastically deformable conduit into the chamber, the diaphragm pumpdraws the fluid from the upstream fluid source container.

In accordance with further embodiments, forces of gravity can be used asa way to fill the chamber of the diaphragm pump. For example, thecontainer of fluid can be disposed above the diaphragm pump.Accordingly, negative pressure may not be needed to draw fluid into thechamber.

As previously discussed, subsequent to drawing the fluid into thechamber of the diaphragm pump, the controller hardware applies pressureto the chamber of the diaphragm pump to deliver the fluid in the chamberdownstream to the peristaltic pump.

In yet further embodiments, to provide precise fluid flow control over alarge possible range, the controller hardware measures a flow rate offluid delivered to the recipient based upon measurements of remainingportions of fluid in the chamber over time. For example, in oneembodiment, the controller hardware is operable to measure a flow rateof the fluid expelled from the chamber of the diaphragm pump downstreamto the segment of the fluid conduit. As previously discussed, aperistaltic pump element of the peristaltic fluid pump controllablyblocks a flow of the fluid received from the diaphragm pump to therecipient. The controller hardware utilizes the measured flow rate ofthe fluid (as detected from measuring respective remaining portions offluid in the chamber of the diaphragm pump) to control (adjust) a sweeprate of moving the peristaltic pump element along the segment of thefluid conduit to provide delivery of fluid from the peristaltic pumpelement (and corresponding elastically deformable conduit) to therecipient as specified by a desired flow rate setting (such as a userselected rate).

If the measurement of fluid flowing through the diaphragm pump isgreater than the desired flow rate setting, the controller hardwaredecreases the rate of sweeping the peristaltic pump element (whichdirectly controls a rate of delivering fluid to a recipient).Conversely, if the measurement of the fluid flowing through thediaphragm pump as detected by the controller hardware is less than thedesired flow rate setting, the controller hardware increases the rate ofsweeping the peristaltic pump element. Accordingly, in one embodiment,the measured rate of fluid flow through the diaphragm pump can be usedas a basis to control the downstream peristaltic pump to provideaccurate fluid flow.

In accordance with yet further embodiments, the controller hardware, ateach of multiple measurement times between a first time of filling ofthe chamber and a next successive time of filling the fluid into thechamber from a fluid source, temporarily changes a magnitude of thepressure at each of multiple sample windows to the chamber to measure arate of delivering the fluid from the chamber downstream to the segment.More specifically, according to one embodiment, the controller hardwarefurther controls the peristaltic pump element in contact with thesegment of fluid conduit to continuously move along a length of thesegment to provide corresponding continuous flow of fluid from thesegment to the recipient in a time window. During each of multiplemeasurement windows, the controller hardware measures a respectiveportion of fluid remaining in the diaphragm pump to determine arespective fluid flow rate.

The controller hardware utilizes the respective measured portions offluid remaining in the diaphragm pump as measured during the multiplemeasurement windows to calculate a rate of fluid delivered by theperistaltic fluid pump to the recipient. As previously discussed, in oneembodiment, the peristaltic fluid pump can be configured to include acorresponding peristaltic pump element in physical contact with thesegment of fluid conduit, the pump element controlling an amount of thefluid received at the elastically deformable conduit from the diaphragmpump.

Embodiments herein including a diaphragm pump (to measure a fluiddelivery rate) and a peristaltic fluid pump (to control physical pumpingtransfer of fluid to a recipient) are advantageous over conventionaltechniques. For example, according to embodiments herein, inclusion of adiaphragm pump provides a way to measure a flow rate of fluid, providesa way (using negative pressure) to draw fluid from a source, andprovides a constant and reliable pressure of fluid to the inlet of aperistaltic fluid pump.

The fluid delivery apparatus and corresponding methods as describedherein provide one or more of the following advantages over conventionaltechniques: i) fast start and stop time to reach desired delivery flowrate set point, ii) large dynamic range to control flow rates from 0.1or lower to 1200 or higher, iii) flow rate control that is immune toinlet or outlet pressure changes, iv) flow rate control that is immuneto large variations in fluid properties (such as viscosity), real-timeflow measurement for improved safety, and so on.

These and other more specific embodiments are disclosed in more detailbelow.

Note that any of the resources as discussed herein can include one ormore computerized devices, fluid delivery systems, servers, basestations, wireless communication equipment, communication managementsystems, workstations, handheld or laptop computers, or the like tocarry out and/or support any or all of the method operations disclosedherein. In other words, one or more computerized devices or processorscan be programmed and/or configured to operate as explained herein tocarry out different embodiments of the invention.

Yet other embodiments herein include software programs to perform thesteps and operations summarized above and disclosed in detail below. Onesuch embodiment comprises a computer program product including anon-transitory computer-readable storage medium (i.e., any physicalcomputer readable hardware storage medium) on which softwareinstructions are encoded for subsequent execution. The instructions,when executed in a computerized device (e.g., computer processinghardware) having a processor, program and/or cause the processor toperform the operations disclosed herein. Such arrangements are typicallyprovided as software, code, instructions, and/or other data (e.g., datastructures) arranged or encoded on a non-transitory computer readablestorage medium such as an optical medium (e.g., CD-ROM), floppy disk,hard disk, memory stick, etc., or other a medium such as firmware orshortcode in one or more ROM, RAM, PROM, etc., or as an ApplicationSpecific Integrated Circuit (ASIC), etc. The software or firmware orother such configurations can be installed onto a computerized device tocause the computerized device to perform the techniques explainedherein.

Accordingly, embodiments herein are directed to a method, system,computer program product, etc., that supports operations as discussedherein.

One embodiment herein includes a computer readable storage medium and/orsystem having instructions stored thereon. The instructions, whenexecuted by computer processor hardware, cause the computer processorhardware to: control magnitudes of pressure in a first volume and asecond volume, the first volume being of a known magnitude, the secondvolume being of an unknown magnitude; estimate a temperature of gas inthe first volume and a temperature of gas in the second volume based onmeasurements of pressure in the first volume and measurements ofpressure in the second volume; and calculate a magnitude of the secondvolume based on measured pressures of the gases and estimatedtemperatures of gases in the first volume and the second volume.

Another embodiment herein includes a computer readable storage mediumand/or system having instructions stored thereon. The instructions, whenexecuted by computer processor hardware, cause the computer processorhardware to: initiate drawing fluid into a chamber of a diaphragm pump;during a delivery phase of pumping the fluid in the chamber to a targetrecipient, applying pressure to the chamber; and at multiple differenttimes during the delivery phase, temporarily discontinuing applicationof the pressure to the chamber to calculate how much of the fluid in thechamber has been pumped to the target recipient.

Yet another embodiment herein includes a computer readable storagemedium and/or system having instructions stored thereon. Theinstructions, when executed by computer processor hardware, cause thecomputer processor hardware to: control magnitudes of pressure in afirst volume and a second volume to be dissimilar, the first volumebeing of a known magnitude, the second volume being of an unknownmagnitude; initiate opening a valve between the first volume and thesecond volume to equalize a pressure in the first volume and the secondvolume; estimate a temperature of gas in the first volume and atemperature of gas in the second volume based on a measured pressure inthe first volume and measured pressure of the second volume; andcalculate a magnitude of the second volume based on measured pressuresof the gases and estimated temperatures of the gases in the first volumeand the second volume.

The ordering of the operations above has been added for clarity sake.Note that any of the processing steps as discussed herein can beperformed in any suitable order.

Other embodiments of the present disclosure include software programsand/or respective hardware to perform any of the method embodiment stepsand operations summarized above and disclosed in detail below.

It is to be understood that the system, method, apparatus, instructionson computer readable storage media, etc., as discussed herein also canbe embodied strictly as a software program, firmware, as a hybrid ofsoftware, hardware and/or firmware, or as hardware alone such as withina processor, or within an operating system or within a softwareapplication.

As discussed herein, techniques herein are well suited for use indelivering fluid to a recipient. However, it should be noted thatembodiments herein are not limited to use in such applications and thatthe techniques discussed herein are well suited for other applicationsas well.

Additionally, note that although each of the different features,techniques, configurations, etc., herein may be discussed in differentplaces of this disclosure, it is intended, where suitable, that each ofthe concepts can optionally be executed independently of each other orin combination with each other. Accordingly, the one or more presentinventions as described herein can be embodied and viewed in manydifferent ways.

Also, note that this preliminary discussion of embodiments hereinpurposefully does not specify every embodiment and/or incrementallynovel aspect of the present disclosure or claimed invention(s). Instead,this brief description only presents general embodiments andcorresponding points of novelty over conventional techniques. Foradditional details and/or possible perspectives (permutations) of theinvention(s), the reader is directed to the Detailed Description sectionand corresponding figures of the present disclosure as further discussedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example diagram illustrating a fluid delivery systemaccording to embodiments herein.

FIG. 2 is an example diagram illustrating more specific details ofcomponents and partitioning in a fluid delivery system according toembodiments herein.

FIG. 3 is an example diagram illustrating details of a diaphragm pumpused in a fluid delivery system according to embodiments herein.

FIG. 4 is an example diagram illustrating a change in hypothetical gastemperatures during a fluid measurement cycle according to embodimentsherein.

FIG. 5A is an example timing diagram illustrating application ofdifferent pressure to a diaphragm pump over time to deliver fluid to atarget recipient according to embodiments herein.

FIG. 5B is an example timing diagram illustrating application ofdifferent pressure to a diaphragm pump over time to deliver fluid to atarget recipient according to embodiments herein.

FIG. 6 is an example timing diagram illustrating temporary terminationor reduction of applying positive pressure to a diaphragm pump andestimation of gas temperatures according to embodiments herein.

FIG. 7 is a diagram illustrating an example computer architecture inwhich to execute any of the functionality according to embodimentsherein.

FIGS. 8-10 are example diagrams illustrating methods facilitating flowcontrol measurement and management according to embodiments herein.

FIG. 11 is an example diagram of implementing a diaphragm pump and apositive displacement pump to deliver fluid to a respective recipientaccording to embodiments herein.

FIG. 12 is an example diagram illustrating drawing of fluid from arespective fluid source into a chamber of a diaphragm pump according toembodiments herein.

FIG. 13 is an example diagram illustrating application of positivepressure to the chamber of the diaphragm pump to convey fluid to arespective downstream positive displacement pump according toembodiments herein.

FIG. 14 is an example diagram illustrating motion of a mechanical pumpelement to deliver fluid (as received from a diaphragm pump) to adownstream recipient according to embodiments herein.

FIG. 15 is an example timing diagram illustrating timing windowsassociated with multiple pump cycles and multiple measurement windowswithin each cycle according to embodiments herein.

FIG. 16 is an example diagram illustrating control of a respectivepositive displacement pump based upon a calculated fluid flow rate offluid delivered by a respective diaphragm pump according to embodimentsherein.

FIG. 17 is an example diagram illustrating a method of delivering fluidto a respective recipient using a combination of a diaphragm pump and apositive displacement pump according to embodiments herein.

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments herein, as illustrated in theaccompanying drawings in which like reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale, with emphasis instead being placed uponillustrating the embodiments, principles, concepts, etc.

DETAILED DESCRIPTION AND FURTHER SUMMARY OF EMBODIMENTS

The fluid delivery system as described herein uses a system of valves,variable flow restrictions, reference volumes, direct pressuremeasurements, etc., to accurately deliver intravenous fluids to arecipient such as a patient. Typically fluids are introduced to thepatient through a vein in the hand or arm. The pressure in the vein istypically on the order of 5 mm of Hg above atmosphere.

Conventional fluid pumps currently available in the market require thata respective fluid source be in a prescribed location with respect tothe pump. Likewise, the pump must be in a prescribed location withrespect to the patient. Variation in either source location ordownstream pressure conditions can cause flow rate inaccuracy due to theaffects of system pressures on the pumping mechanism. It is desirablefor many reasons in a clinical setting for the pump to be able todeliver the fluid to the patient irrespective of the source or outletpressure conditions. In certain instances when a peristaltic fluid pumpis used, wear-out of respective elastic regions in the peristaltic pumpcan cause inaccuracy as well. More specifically, as respective tubingbecomes worn and fatigued, it doesn't rebound fully. In such aninstance, the “stroke” of each cycle (volume of fluid delivered in eachstroke cycle) is diminished.

Embodiments herein use compressed gas (air) to induce the requireddifferential pressures needed to move the fluid into the patient under awide range of relative positions of the pump, the patient, and the fluidsource. The fluid to be delivered may be below the patient or above thepatient. The pump may be above or below the patient regardless of thefluid location. In certain instances, it is desirable that the fluid bedelivered with as low a pressure as possible and at a continuous flowrate. The pump is able to use low pressure and accommodate a variety ofrelative pump and/or patient positions because the system can measureflow rate and adjust for any variations away from the target flow rate.

There are primarily two types of IV pumps on the market today; syringeand linear peristaltic pumps. Both are positive displacement pumps,which can present very high pressures to the patient in manycircumstances. There are many limitations of this technology. As anexample, in order to mitigate this risk, pressure sensors are added todetect dangerously high pressures and stop the pump. Due to theconfiguration of this technology and the elasticity of the tubing, largeboluses of fluid are often injected to the patient inadvertently. Incontrast, by using drive pressure directly to push the fluid to thepatient rather than a rigid mechanical piston any disturbances stop thepump directly without the need for a detection system.

Now, more specifically, FIG. 1 is an example diagram illustrating afluid delivery system according to embodiments herein.

As shown, fluid delivery environment 101 includes fluid delivery system100. Fluid delivery system 100 includes fluid source 120-1, fluid source120-2, and recipient 108. Fluid delivery system 100 includes controller140 as well as cassette 104, facilitating delivery of fluid from one ormore fluid sources 120 to the recipient 108.

In one embodiment, the cassette 104 is a disposable cartridge insertedinto a cavity of a housing of the fluid delivery system 100. Duringdelivery, fluid from the different fluid sources 120 is limited tocontacting (disposable tube set including) cassette 104, tubes 103, andits corresponding components as further discussed below. When deliveringfluid to a different patient, a caregiver inserts a new cassette intothe cavity of fluid delivery system 100. The new cassette includes acorresponding set of new (sterile) tubes. Thus, the fluid deliverysystem 100 can be used for many patients without having to be cleaned.

As mentioned, during operation, the controller 140 of fluid deliverysystem 100 controls delivery of fluid from one or more fluid sources 120(such as fluid source 120-1 and/or fluid source 120-2) to recipient 108.As shown in this example embodiment, tube 105-1 conveys fluid from fluidsource 120-1 to cassette 104. Tube 105-2 conveys fluid from fluid source120-2 to cassette 104. Note that fluid source 120-1 and fluid source120-2 can store the same or different fluids.

The controller 140 controls one or more components in cassette 104 todeliver fluid received from fluid source 120-1 and/or fluid source 120-2through tube 105-3 to recipient 108.

Control System:

By way of a non-limiting example, a mass flow based measurement systemtakes into account the ideal gas laws and mass conservation. Theequations hold for a closed system.

$\begin{matrix}{{M_{a\; 1} + M_{b\; 1}} = {M_{a\; 2} + M_{b\; 2}}} & \left( {{equation}\mspace{14mu} 1} \right) \\{{PV} = {\left. {MRT}\rightarrow M \right. = \frac{PV}{RT}}} & \left( {{equation}\mspace{14mu} 2} \right)\end{matrix}$

R is a constant, so the equations factor down to:

$\begin{matrix}{{{\frac{P_{a\; 1}}{T_{a\; 1}}V_{a}} + {\frac{P_{b\; 1}}{T_{b\; 1}}V_{b}}} = {{\frac{P_{a\; 2}}{T_{a\; 2}}V_{a}} + {\frac{P_{b\; 2}}{T_{b\; 2}}V_{b}}}} & \left( {{equation}\mspace{14mu} 3} \right)\end{matrix}$

Estimation of temperatures as disclosed herein enables quickmeasurements and allows the device to operate without stopping the flowduring measurements by taking into account the full system states (suchas temperature), rather than assuming that they remain constant throughthe cycle.

More specifically, in one embodiment, an appropriate drive pressure canbe applied to a drive chamber side of a diaphragm pump to initiatedelivery of fluid in a fluid chamber side of the diaphragm pump to atarget recipient. Further embodiments herein can include discontinuingapplication of the pressure to the drive chamber at one or more timesduring a delivery cycle to perform a volume check to identify how muchof the fluid is present in the fluid chamber of the diaphragm pump overtime.

In one embodiment, the flow rate of fluid pumped to a target recipientequals the change in volume of the drive chamber over time.

During times of discontinuing application of the pressure to thediaphragm pump, embodiments herein can include taking into accountchanges in temperature of the gases (as a result of changing pressures)in one or more chambers when calculating the flow rate of delivering thefluid to the target recipient.

In one embodiment, a mass balance measurement is dependent on thetemperature of the working fluid. Given required measurement speed notedabove, the gas experiences adiabatic heating and cooling during themeasurement cycle. It may be difficult if not impossible to measure(with a temperature sensor) the gas temperature directly in the timeframe needed; therefore a thermal estimator is used to predict the gastemperature. In other words, the temperature of gases in one or morevolumes as discussed herein can change so quickly that a physicaltemperature sensor is unable to detect a respective change intemperature.

FIG. 4 is a hypothetical example diagram illustrating gas temperaturesin different resources during a delivery cycle. As described herein, oneor more temperatures can be estimated based on known system informationas discussed in more detail below.

In one embodiment, there are several additions to the ideal gas lawapproach that are used to achieve the required performancecharacteristics for a safe and reliable infusion pump. First there arecommon conditions when the flow rate is low and the outlet pressure islow such as when the pump is significantly higher than the patient. Inthis case, the required drive or pumping pressure is also very low. Verylow drive pressures are difficult to measure with common low costpressure transducers and it is very difficult to accurately control andmaintain low pressure in the positive tank. At higher flow rates orhigher outlet pressure, the drive pressures needed are much higher. Thiswide dynamic range makes it difficult to maintain pressure measurementresolution.

In order to: i) achieve all of the desired flow rate range given therelatively wide range of outlet pressure, ii) maximize pressuremeasurement resolution, and iii) maintain a driving pressure high enoughto avoid low pressure measurements near atmosphere, embodiments hereincan include a variable flow restriction that is added downstream of thepump chamber.

By way of a non-limiting example, this flow restriction can be avariable orifice. Given a desired set point flow rate, the variablefluid restriction opening is changed to maintain a minimum drivepressure. This variable fluid restriction further serves as a safetymechanism that can be positively shut or closed if desired. Anotherrequirement of infusion systems may be to maintain continuous flow. Inone embodiment, the fluid delivery system as discussed herein does notstop the pumping during a flow rate measurement. Thus, embodimentsherein can include providing a continuous or substantially continuousflow of fluid delivery to a respective target recipient.

In order not to introduce measurement error, the volume measurementcycle can be performed extremely fast such as on the order ofmilliseconds. According to embodiments herein, a measurement cycle canbe less than 200 milliseconds. The fill cycle, such as filling thechamber of the diaphragm pump with fluid, also can be performed veryfast to minimize flow variation.

When the gases are moved at this high speed for all of the reasons abovethe isothermal Ideal Gas Law and Boyle's Law begin to breakdown.Specifically the assumption that the gas is isothermal is no longertrue. It is observed that the gas experiences adiabatic heating andcooling during the measurement cycle. As previously discussed,embodiments herein include estimating gas temperatures to compensate forthese errors.

In order to account for the temperature effects due to adiabatic heatingand cooling of the gas the pressure and volume relationships aretransformed as described above to yield:

$\begin{matrix}{V_{pc} = {V_{com}\frac{\left( {\frac{P_{{com}\; 2}}{T_{{com}\; 2}} - \frac{P_{{com}\; 1}}{T_{{com}\; 1}}} \right)}{\left( {\frac{P_{{pc}\; 1}}{T_{{pc}\; 1}} - \frac{P_{{pc}\; 2}}{T_{{pc}\; 2}}} \right)}}} & \left( {{equation}\mspace{14mu} 4} \right)\end{matrix}$

By way of a non-limiting example, the temperature can be estimated bytracking the system state variables at each time step of the controlloop. The physical parameters of the delivery system, such as volume,orifice size, and heat transfer coefficients combined with the measuredpressures allow the system to calculate an estimated temperature in eachof the gas volumes at any point during the pumping cycle using thefollowing energy balance equation:

$\begin{matrix}{\frac{{dT}_{i}}{dt} = {{\frac{1}{M_{i}C_{v}}\left\lbrack {{C_{p}{\sum\limits_{j}\; {T_{j}Q_{ji}}}} - {C_{p}T_{i}Q_{out}} - {C_{v}{T_{i}\left( {Q_{in} - Q_{out}} \right)}} + {H\left( {T_{wall} - T_{i}} \right)}} \right\rbrack} - {{\left( {\frac{C_{p}}{C_{v}} - 1} \right) \cdot \frac{T_{i}}{V_{i}}}\frac{{dV}_{i}}{dt}}}} & \left( {{equation}\mspace{14mu} 5} \right)\end{matrix}$

Where:

V=volume

Cv=specific heat at constant volume

Cp=specific heat at constant pressure

T=temperature

Q=mass flow

H=heat transfer coefficient

More Detailed Description of Embodiments

In one non-limiting example embodiment, the fluid pumping system asdescribed herein is centered around a pumping chamber(“IPC”—Intermediate Pumping Chamber) that consists of a volumebifurcated by a flexible diaphragm. One side of the IPC is connected tothe pneumatic portion of the fluidic system. The other side of the IPCis connected to the hydraulic portion of the fluidic system. Hydraulicpumping is achieved by applying alternating positive and negativepressure to the pneumatic side of the IPC, thus moving the diaphragmback and forth (or in and out).

FIG. 2 is a more specific example diagram illustrating componentsdisposed in a fluid delivery system and corresponding disposablecassette according to embodiments herein.

As previously discussed, the controller 140 of the fluid delivery system100 controls operation of diaphragm pumps 130 and 131 in disposablecassette 104 to precisely deliver fluid from one or more fluid sourcessuch as fluid source 120-1 and fluid source 120-2 to a respectiverecipient 108.

In one embodiment, the flow of fluid through the system is controlled byadjustments to the drive pressure from the Positive Tank 170-1 and avariable hydraulic resistor (component such as fluid resistor 115) thatis controlled by a motor or other suitable resource. Flow rate ismeasured using periodic volume calculations described below, and thecontrol parameters are adjusted accordingly to drive the error betweenmeasured flow rate and target flow rate to zero.

Pump Cycle Overview

In accordance with yet further embodiments, a pump cycle is defined as amotion of drawing fluid into a diaphragm pump and then applying pressureto the diaphragm pump to deliver the fluid to a recipient. In accordancewith a specific non-limiting example embodiment, a pump cycle can bedefined as at least partially moving of the membrane 127 in thediaphragm pump 130 from one extreme (such as “full”) to another extreme(such as “empty”).

As shown in FIG. 2 and more specific FIG. 3, membrane 127 divides thediaphragm pump 130 to include chamber 130-1 and chamber 130-2. Membrane127 prevents fluid in chamber 130-1 from passing to chamber 130-2, andvice versa.

The membrane 127 dividing diaphragm pump 130 into chamber 130-1 andchamber 130-2 is flexible. When a negative pressure is applied tochamber 130-2, the volume of chamber 130-1 expands and draws fluid fromfluid source 120-1 into chamber 130-1.

Conversely, when a positive pressure is applied to chamber 130-2, thevolume of chamber 130-1 decreases expelling fluid from chamber 130-1downstream to a respective recipient 108.

The total volume or capacity of chamber 130-1 and chamber 130-2 issubstantially constant regardless of the position of the membrane 127.Based on knowing the volume of fluid in chamber 130-2, one is able todetermine a corresponding volume of chamber 130-1. For example, if thetotal volume of the diaphragm pump 130 is Vtotal, and the volume ofchamber 130-2 is V2, the fluid delivery system 100 can determine thevolume of chamber 130-1 by subtracting V2 from Vtotal.

Diaphragm pump 131 operates in a similar manner as diaphragm pump 130.Membrane 128 divides the diaphragm pump 131 to include chamber 131-1 andchamber 131-2. Membrane 128 prevents fluid in chamber 131-1 from passingto chamber 131-2, and vice versa.

The membrane 128 dividing diaphragm pump 131 into chamber 131-1 andchamber 131-2 is flexible. When a negative pressure is applied tochamber 131-2, the chamber 131-1 draws fluid from fluid source 120-2into chamber 131-1. Conversely, when a positive pressure is applied tochamber 131-2, the diaphragm pump 131 expels fluid from chamber 131-1downstream to a respective recipient 108.

In a similar manner as previously discussed for diaphragm pump 130, thetotal volume or capacity of chamber 131-1 and chamber 131-2 issubstantially constant regardless of the position of the membrane 128.Based on knowing the volume of fluid in chamber 131-2, the controller140 is able to determine a corresponding volume of chamber 131-1. Forexample, if the total volume of the diaphragm pump 131 is Vtotal, andthe volume of chamber 131-2 is determined as being V2, the fluiddelivery system 100 can determine the volume of chamber 131-1 bysubtracting V2 from Vtotal.

In this example embodiment, as shown in FIG. 2, temperature sensor 152measures a temperature (e.g., TTC) of gas in chamber 150 (common tank)and provides a baseline from which to estimate the temperatures of gasesin one or more of the following resources: chamber 150, pump chamber130-2, positive tank 170-1, negative tank 170-2, etc.

As further discussed below, estimation of the temperature enables a moreaccurate assessment of how much of fluid in pump chamber 130-1 has beenpumped in a direction towards the target recipient 108 over conduit path138 (such as a path from diaphragm pump 130 through a combination ofcheck valve 125-2, filter 112, fluid resistor, gas detection resource110, and tube 105-3 to recipient 108).

Initially, to fill the chamber 130-1 with fluid from fluid source 120-1,the controller 140 of fluid delivery system 100 applies a negativepressure or vacuum to chamber 130-2. At such time, pump chamber 130-2reduces in volume, causing the chamber 130-1 to fill with fluid receivedfrom fluid source 120-1 through check valve 125-1. Check valve 125-1prevents fluid from flowing in a backward direction from diaphragm pump130 to fluid source 120-1. Check valve 125-2 prevents fluid from flowingin a backward direction from conduit path 138 to the pump chamber 130-1.

Assume that prior to filling, the chamber 130-1 is substantially emptyof fluid. In one embodiment, to draw fluid into chamber 130-1 withnegative pressure from tank 170-2 as discussed above, the controller140-1 generates respective control signals V1 and V5 to open valve 160-1and 160-5 (while all other valves are closed) to draw fluid from fluidsource 120-1 and check valve 125-1 into chamber 130-1.

Subsequent to chamber 130-1 being filled with fluid, the controller 140controls settings of the valves 160 to apply a positive pressure fromtank 170-1 to chamber 130-2 of diaphragm pump 130. For example, viageneration of control signals V4 and V5, the controller 140 opens valves160-4 and 160-5 and closes all other valves. The flow of gas frompositive tank 170-1 to pump chamber 130-2 causes pumping of fluid fromchamber 130-1 through check valve 125-2 along conduit path 138 to thetarget recipient 108. As previously discussed, during application ofpositive pressure to chamber 130-2, check valve 125-1 prevents fluid inchamber 130-1 from flowing back into fluid source 120-1.

As shown, the conduit path 138 through cassette 104 can include filterresource 112 that eliminates air and/or particulate matter in the fluidfrom being pumped to the target recipient 108.

Additionally conduit path 138 can include an in-line flow resistor 115.In one embodiment, the controller 140 utilizes the in-line flow resistoras one means to control a rate of delivering fluid to the targetrecipient 108. For example, at a given driving pressure in chamber130-2, to decrease a rate of flow, the controller 140 increases aresistance of the in-line flow resistor 115. To increase a flow rate offluid from the chamber 130-1 to the target recipient 108, the controller140 decreases a resistance of the in-line flow resistor 115.

Note that drive pressure in chamber 130-2 is another way to control arate of delivering fluid to the target recipient 108. At a givenposition of an in-line flow resistor 115, the controller can use airpump 180 and pressure gauge 135-4 to set a target drive pressure inpositive tank 170-1. That drive pressure can then be applied to pumpchamber 130-2 (by opening valve 160-5) to drive the fluid in chamber130-1 to target recipient 108. To increase a flow rate of fluid from thechamber 130-1 to the target recipient 108, the controller 140 can beconfigured to increase the drive pressure in positive tank 170-1. Todecrease a flow rate the controller 140 can be configured to decreasethe drive pressure in positive tank 170-1.

Note that conduit path 138 also can include gas detector resource 110.The gas detector resource 110 can be configured to detect presence ofair (or other gases) in the fluid being pumped through conduit path 138to the target recipient 108. Based on feedback from the gas detectorresource 110 as monitored by the controller 140, the controller 140 canbe configured to sound an alarm in the event of detecting presence ofgas in the fluid pumped to the target recipient 108.

During a delivery phase, the controller 140 can be configured to mainlyapply pressure to chamber 130-2 with gas from tank 170-1 or tank 150 tocause the fluid in chamber 130-1 to be pumped to the target recipient108. Delivery of the fluid in chamber 130-1 through conduit path 138 totarget recipient 108 can be controlled by the controller 140 inaccordance with a pre-selected fluid delivery rate. In other words, thecontroller 140 controls positive pressure applied chamber 130-1 tocontrol a respective fluid flow rate. As further discussed below,embodiments herein can include at least temporarily discontinuingapplication of pressure to chamber 130-2 in order to perform ameasurement of fluid remaining in chamber 130-1. As shown and discussed,discontinuing application of pressure to chamber 130-2 can at leasttemporarily reducing a pressure in chamber 130-2.

During a fluid delivery phase, the controller 140 supplies asubstantially constant pressure to the chamber 130-2. Because themembrane 127 is flexible, the pressure in chamber 130-2 exerts a forceon the fluid in chamber 130-1. In general, via application of theappropriate pressure to chamber 130-2, the controller 140 is able tofairly accurately pump the fluid at a desired flow rate. However, incertain situations, the delivery system 100 can be perturbed, resultingin errors in the flow rate. For example, as previously mentioned, thefluid source 120-1 may be squeezed, the elevation of fluid source 120-1may change, etc. Any of these conditions can impact an accuracy of adesired fluid delivery rate.

Note that in addition to applying positive pressure to the pump chamber130-2 during a fluid delivery phase, embodiments herein can includeoccasionally checking how much of the fluid drawn into the chamber 130-1has been pumped towards the target recipient 108 through conduit path138. This enables the controller 140 to accurately determine the actualflow rate of fluid, even during times when the system conditions areperturbed.

More specifically, one way to measure a fluid delivery rate during arespective delivery phase is to repeatedly measure how much of the fluidin the chamber 130-1 has been pumped towards target recipient 108 onconduit path 138 at one or more MEASUREMENT times during the deliveryphase. For example, the controller 140 the controller can initiatechecking the volume of gas in chamber 130-2 over multiple sample timesof a positive pressure delivery cycle. Because it is known how much gasis initially in the chamber 130-2 at the beginning of a delivery phase,and based on calculating how much gas is in chamber 130-2 at differenttimes, etc., the controller is able to accurately measure a rate ofpumping or delivering the fluid from fluid source 120-1 over conduitpath 138 to the target recipient 108 in between times of filling thechamber 130-2. Thus, the controller 140 is able to accurately measurefluid delivery in very small increments of time between successivecycles of refilling the chamber 130-1 with additional fluid.

In one embodiment, as previously discussed, the total volume of thediaphragm pump 120-1 including chamber 130-1, chamber 130-2 and conduitthere between is a known quantity. One embodiment herein includescalculating how much fluid remains in chamber 130-1 based on knowing thevolume of chamber 130-2. That is, the volume of the chamber 130-1 can becalculated by subtracting the volume of chamber 130-1 from the totalvolume of diaphragm pump 130. As discussed below, the volume of chamber130-2 is initially an unknown quantity but is calculated based onpressure and estimated temperature.

FIG. 5A is an example diagram illustrating fluid measurements duringfluid delivery according to embodiments herein. As shown, graph 510-1illustrates application of pressure for more than 95% of a deliverycycle. PC represents the pressure of gas in chamber 130-2; COMrepresents the pressure of gas in the chamber 150.

In between times of applying pressure to chamber 130-2 (such as timeslabeled as FLUID DELIVERY), the controller 140 of fluid delivery system100 periodically or occasionally, at multiple times, performs ameasurement (labeled as MEASUREMENT) to determine a volume of chamber130-2 of diaphragm pump 130. By way of non-limiting example embodiment,the controller 140 initiates applying an approximately constant pressureduring FLUID DELIVERY portions of a fluid delivery cycle while theapplied pressure to chamber 130-2 is reduced briefly during eachrespective MEASUREMENT.

In this example embodiment, graph 520-1 illustrates changes intemperature of respective gases that occur during each of themeasurements. For example, Tcom represents the estimated temperature ofthe gas in the chamber 150; Tpc represents the temperature of gas in thechamber 130-2.

In general, in one non-limiting example embodiment, the duty cycle ofperforming measurements versus delivering fluid is relatively small.That is, in one non-limiting example embodiment, most of a fluiddelivery cycle (delivery phase) can be used to deliver correspondingfluid in chamber 130-1 of pump 130 to recipient 108. For a small portionof the delivery cycle, the controller 140 operates respective resourcesto perform a corresponding volume MEASUREMENT of the chamber 130-2 asshown. Recall that after a volume of the chamber 130-2 is known, thevolume of chamber 130-1 can easily be determined.

FIG. 5B is an example diagram illustrating more particular details of afluid delivery cycle according to embodiments herein.

Graph 510-2 shows the pressures measured in the system during a fluiddelivery cycle. Graph 520-2 shows the estimated temperatures measured inthe system during a fluid delivery cycle.

For the discussion here, the focus will be on pumping from the lefthydraulic channel (e.g., from fluid source 120-1, through check valve125-1, to diaphragm pump 130, through conduit path 138 to the targetrecipient 108), but the same patterns, behaviors and measurements applyto the right channel (e.g., from fluid source 120-2, through check valve125-2, to diaphragm pump 131, to the target recipient 108) as well.

As previously discussed, one or more diaphragm pumps can be operated inany suitable manner to deliver one or more fluids to a target recipient108. For example, the controller 140 can individually and accuratelycontrol the flow rate of each of the fluids delivered to the targetrecipient 108.

In one non-limiting example embodiment, the controller 140 can pump afirst fluid from fluid source 120-1 to the target recipient 108 at afirst fluid delivery rate; the controller 140 can pump a second fluidfrom fluid source 120-2 to the target recipient 108 at a second fluiddelivery rate, the first delivery rate can be different than the seconddelivery rate.

At or around time [A] in FIG. 5B, a delivery cycle begins by resettingthe pressures in the positive tank 170-1 and negative tank 170-2. Thecontroller 140 sets the solenoid valves 160-1, 160-2, 160-3, 160-4, and160-5 (via generation of control signals V1, V2, V3, V4, and V5) to aclosed position. The controller 140 activates (turns ON) air pump 180 tobring the tanks to the desired drive pressure.

At time [B], valves 160-1 (V1) and 160-5 (V5) are opened to apply thepressure in the negative tank 170-2 to the chamber 130-2. The negativepressure draws the diaphragm membrane 127 back towards tank 150, fillingchamber 130-1 with fluid from fluid source 120-1. Check valve 125-1(CV1) opens due to the differential pressure. Fluid such as liquid fromfluid source 120-1 is drawn into the chamber 130-1 of the diaphragm pump130.

At time [C] valves 160-4 (via generation of signal V4) and 160-5 (viageneration of signal V5) are opened to apply the pressure in thepositive tank 170-1 to the chamber 130-2 of the diaphragm pump 130. Thepositive pressure causes check valve 125-1 (CV1) to close and checkvalve 125-2 (CV2) to open. This causes the liquid in the chamber 130-2of the diaphragm pump 130 to flow on conduit path 138 towards the targetrecipient 108 such as a patient.

In one embodiment, some time after the chamber 130-2 of diaphragm pump130 is brought to positive pressure, the controller 140 performs volumecalculations such as at times [D], [E], [F], etc. Aspects of the volumecalculation are discussed in more detail below. As previously discussed,one or more volume calculations can be performed periodically during thetime that the chamber 130-1 is emptying (e.g., during times [C] through[I]).

After the last volume measurement at time [I], or at any time during thedelivery phase, the controller 140 calculates a flow rate from thevolume measurements. Based on the calculated flow rate the controller140 can determine if adjustments are needed to one or both of the twoflow control parameters: target drive pressure in positive tank 170-1,in-line fluid resistance 115.

In general, increasing the pressure of gas in the chamber 130-2 of thediaphragm pump 130 increases the rate of fluid delivery; decreasing amagnitude of gas pressure applied to chamber 130-2 decreases arespective rate of fluid delivery.

Additionally, increasing an amount of fluid resistance provided by fluidresistor 115 reduces a rate at which the fluid in chamber 130-1 isdelivered to the recipient 108;

decreasing amount of fluid resistance provided by fluid resistor 115increases a rate at which the fluid chamber 130-1 is delivered to therecipient 108.

The fluid delivery cycle restarts when the air pump 180 is turned on attime [J] to reset the pressures in the positive tank 170-1 and negativetank 170-2 again.

Measure Cycle Overview

FIG. 6 is an example diagram illustrating a MEASUREMENT (time E) duringa fluid delivery cycle according to embodiments herein.

Graph 610 illustrates gas pressures in each of multiple volumes. In thisexample embodiment, the pressure signal labeled PC in graph 610represents the pressure of a gas in chamber 130-2 as measured bypressure sensor 135-5 (which produces pressure signal P5). The pressuresignal labeled COM in graph 610 represents the pressure of a gas inchamber 150 as measured by pressure sensor 135-3 (which producespressure signal P3).

Graph 620 illustrates estimated temperatures of the respective gases inthe chamber 150 and chamber 130-2.

At the start of a respective fluid delivery cycle, the chamber 150(Common Tank), positive tank 170-1, and the diaphragm pump 130 (e.g.,Left IPC) are all at to the same pressure such as the driving pressureof the system. The driving pressure represents the pressure of the gasapplied to chamber 130-2 prior to time T1.

At point [1] in graph 610, the controller 140 generates control signalsV1, V2, V3, etc., to close all of the valves 160 to isolate the gasvolumes. The controller controls valve 160-3 (via signal V3) to an openstate to vent the chamber 150 (Common Tank) to ambient pressure.

When the pressure in the chamber 150 reaches ambient pressure atapproximately point [2], the controller 140 controls valve 160-3 (viageneration of signal V3) to a closed position again such that all of thegas volumes are again isolated.

After a brief stabilization period (such as approx. 50 milliseconds), atapproximately time, T1, (shown as points [3] and [4]), the controller140 controls valve 160-5 (via generation of signal V5) to an open stateto merge the gas in chamber 130-2 with the gas in chamber 150. The gaspressure in the chamber 130-2 and tank 150 equalize at or around point[5] in graph 610. In one embodiment, the volume of chamber 130-2 andchamber 150 are approximately the same. In this example embodiment,opening of valve 160-5 causes the pressure in the chamber 130-2 toreduce by approximately 50%. The amount of reduction in pressure appliedto chamber 130-2 varies depending on a volume of chamber 130-2 and avolume of chamber 150.

After another brief stabilization period (such as approx. 50milliseconds or at point [6]), the controller 140 controls valve 160-4(via generation of signal V4) to an open state to connect the chamber130-2 (Left IPC) and the chamber 150 to the positive tank 170-1 to bringall three gas volumes up to the driving pressure again, during which thepressure in the chamber 130-2 causes the chamber 130-1 to pumprespective fluid to the target recipient 108. Thus, embodiments hereininclude at least temporarily discontinuing application of the drivepressure in order to obtain pressure measurements at different times.

In one embodiment, the actual volume calculation produced by thecontroller 140 occurs based on measurements of pressure collected by thecontroller 140 at or around points [3], [4], and [5].

At substantially time T1 or point [3], the controller 140 receivessignal P5 generated by pressure sensor 135-5 to determine the pressurePpc of the gas applied to chamber 130-2.

At substantially time T1 or point [4], the controller 140 receivessignal P3 generated by pressure sensor 135-3 to determine the pressurePcom of the gas in chamber 150.

At substantially time T2 or point [5], the controller 140 receivessignal P3 or P5 generated by pressure sensor 135-3 or pressure sensor135-5 to determine the pressure Pmerge of the gas in chamber 150.

According to one embodiment, the controller 140 determines the volume ofgas in chamber 130-2 using isothermal ideal gas laws as follows:

P ₁ V ₁ =P ₂ V ₂  (equation 6)

For:

-   -   V_(pc)=Unknown volume of the chamber 130-2 of diaphragm pump 130        (left IPC)    -   V_(com)=the known volume of the chamber 150 (Common Tank)    -   P_(pc)=pressure of the chamber 130-2 Left IPC at point [4]    -   P_(com)=pressure of the chamber 150 (Common Tank) at point [3]    -   P_(merge)=P_(pc)=P_(com) pressure when the two chambers (130-2        and 150) are equalized at point [5] (equation 7)

V _(pc) P _(pc) +V _(com) P _(com) =V _(pc) P _(merge) +V _(com) P_(merge)  (equation 7)

.

.

.

V _(pc) =V _(com) P _(merge) −P _(com) /P _(pc) −P _(merge)  (equation8)

An isothermal calculation assumes that all transient thermal effects inthe system have had time to dissipate. This dissipation can take on theorder of seconds to occur, depending on the details of the system. Ifthe volume calculation is performed prior to the system returning tothermal equilibrium, the residual temperature differences will introduceerrors in the volume calculation, which will in turn cause errors in theresultant flow rate calculation.

In accordance with one embodiment, in order to achieve the range of flowrates required in an infusion pump system, and to minimize errors due tovolume changes during the measurement cycle, the current embodiment canbe configured to calculate a volume of fluid pumped to the targetrecipient 108 before the transient thermal effects have dissipated. Inorder to maintain volume calculation accuracy, embodiments herein takeinto account thermal effects to produce a more accurate fluid deliveryrate.

In one embodiment, the temperature changes in the gas happen too fast tobe measured by standard thermal sensors. In other words, thermal sensorsmay not be able to accurately measure fast changing temperatures of thegases in tank 150, chamber 130-2, etc., during a respective pressurechanges shown in graph 600. To address this issue, one embodiment hereinincludes estimating temperatures of the volumes of interest to calculatean actual fluid delivery rate. As mentioned, the temperature sensor 152measures an average temperature of gas in the common tank 150. However,due to its thermal mass, the temperature sensor 152 may not be able toaccurately reflect an actual temperature of gas in chamber 150.

There are a number of parameters that affect the temperature of thegases in the different volumes (e.g., tank 150, chamber 130-2, etc.)over time. For example, thermal changes come primarily from 3 sources inthe pneumatic system:

1. Adiabatic heating or cooling due to pressure changes in the chamber

2. Heat transfer between the gas and the chamber wall

3. Volume change due to flow rate out of the IPC chamber

One embodiment herein includes modeling the fluid delivery system 100 toaccurately estimate the temperature of the chambers of interest. Forexample, as mentioned, the change in pressure of chambers (such as pumpchamber 130-2 and chamber 150) as shown and discussed with respect toFIG. 6 causes the temperature of the pump chamber 130-2 and the commontank 150 to vary. More specifically, between point 1 and point 2 in FIG.6, the pressure of the common tank 150 drops significantly, causing thetemperature of the gas, Tcom, in chamber 150 (common tank) to drop. Aspreviously discussed, the pressure of gas in the respective chambers(e.g., P5, P3, etc.) is continuously and accurately measured usingrespective pressure sensors 135-5, 135-3, etc.

In one embodiment, a first model is used to estimate temperature changesin the chambers due to adiabatic heating and/or cooling. In other words,any suitable equations can be used to determine a change in thetemperature of the gases in the chambers as a result of the pressureschanging. Increasing a pressure of a gas causes an increase intemperature; decreasing a pressure of a gas causes a decrease intemperature.

Another parameter affecting the temperature of the gases in the chambersis the thermal characteristics of the chambers themselves and conduitsin between. The dark lines in FIG. 2 represent conduits interconnectingthe different components in fluid delivery system 100. For example, thedark line extending between diaphragm pump 130 and valve 160-5represents a conduit; the dark line between valve 160-5 in chamber 150represents a conduit; and so on. Via respective conduits, each of thecomponents (such as check valve 125-1, diaphragm pump 130, valve 160-5,etc.) in fluid delivery system 100 are interconnected.

According to embodiments herein, the thermal properties of the chambers(e.g., common tank 150, pump chamber 130-2, etc.) can be characterizedand modeled to identify how quickly they sink or source heat when thereis a change in temperature caused by a change in pressure. As anexample, and as discussed, the reduction in the pressure of a tank cancause the temperature of the gas in the tank to decrease. Thetemperature of the tank itself may be higher in magnitude than thetemperature of the gas, resulting in a flow of heat from the tank orchamber to the gas therein. Thermal flow causes the temperature of thegas in the chamber to eventually become the substantially the same asthe temperature in the respective tank over time. Conversely, anincrease in pressure of the tank can cause the temperature to increase.The flow of heat from gas to the tank or chamber decreases thetemperature of the gas.

One embodiment herein includes estimating the temperature of the gas andtaking into account thermal heat flow using a respective thermal model.The thermal model takes into account the transfer of heat from the gasto the respective chamber or tank and/or a transfer of heat from therespective chamber or tank to the gas. The heat transfer will likelyvary depending on the type of material used to fabricate the tanks andrespective interconnections. Certain material such as metal will be morethermally conductive; material such as plastic will be less thermallyconductive.

As discussed above, the changes in the temperature of the gases due tochanges in pressure are deterministic and thus can be accuratelyestimated. However, the flow of energy from tank to gas or from gas totank will impact the temperature. Embodiments herein include producing amore accurate estimate of temperature by taking into account these flowsof energy at different times based on thermal modeling.

Another factor affecting the temperatures of the gases in the chambersis the volume of the pump chamber 130-2 and how quickly it changes overtime due to pumping of the fluid in the diaphragm pump chamber to thetarget recipient. For example, if the fluid in the pump chamber 130-2 ispumped at a very slow rate to target recipient 108, then volume changeeffects are minor or potentially negligible. Conversely, if the fluid inpump chamber 130-1 is pumped at a relatively high rate to the targetrecipient 108, then the volume change effects become more significant.As discussed herein, embodiments herein take into account the volumechanges.

In one embodiment, the controller 140 generates the estimation oftemperatures at discrete points in time such as between one second andone nanosecond. For each time step (i.e., each discrete time ofproducing an estimation of temperature) of the control system, thechange in temperature due to those three sources is calculated for eachpneumatic volume using the measured pressure as an input. The components(e.g., adiabatic effects, heat transfer effects, volume change effects)can be measured individually and/or in combination to produce arespective estimated temperature.

In the following equations subscripts ‘i’ and T are used to denote eachof the pneumatic volumes 130-2, 150, 170-1, 170-2. The subscript ‘i’represents the chamber for which the temperature is being estimated; thesubscript ‘j’ represents the associated chamber. For example, whenestimating a temperature for the pump chamber 130-2, the subscript ‘i’represents the pump chamber 130-2; subscript ‘j’ represents the commontank 150. When estimating a temperature for the common tank 150, thesubscript ‘i’ represents the common tank 150; subscript ‘j’ representsthe pump chamber 130-2, and so on.

By way of a non-limiting example, the temperature at time (n+1) is thencalculated based on that change rate:

$\begin{matrix}{\frac{{dT}_{n}}{dt} = {\left( {{Heat}\mspace{14mu} {Transfer}\mspace{14mu} {Effects}} \right) + \left( {{Pressure}\mspace{14mu} {Change}\mspace{14mu} {Effects}} \right) + \left( {{Volume}\mspace{14mu} {Change}\mspace{14mu} {Effects}} \right)}} & \left( {{equation}\mspace{14mu} 9} \right) \\{T_{n + 1} = {T_{n} + {{dt}\frac{{dT}_{n}}{dt}}}} & \left( {{equation}\mspace{14mu} 10} \right)\end{matrix}$

Heat transfer effects are based on the temperature of the gas in thechamber, the temperature of the chamber wall, and the heat transfercoefficient between the two. For example, in one embodiment:

Heat Transfer Effects H(T _(wall) −T _(i))  (equation 11)

T_(i)=last estimation of temperature for chamber i

H=heat transfer coefficient

T_(wall) ambient temperature T_(tc) as sensed by temperature sensor 152

Pressure change effects are based on the mass flow from once chamber toanother due to pressure differential between the two chambers:

$\begin{matrix}{Q_{ij} = {C_{ij}A_{ij}\sqrt{2{\rho_{i}\left( {P_{i} - P_{j}} \right)}}}} & \left( {{equation}\mspace{14mu} 12} \right) \\{{Q_{in} = {\sum\limits_{j}\; Q_{ji}}}{Q_{out} = {\sum\limits_{j}\; Q_{ij}}}} & \left( {{equations}\mspace{14mu} 13\mspace{14mu} {and}\mspace{14mu} 14} \right) \\{{{Pressure}\mspace{14mu} {Change}\mspace{14mu} {Effects}} = {\frac{1}{M_{i}C_{v}}{\quad\left\lbrack {{C_{p}{\sum\limits_{j}\; {T_{j}Q_{ji}}}} - {C_{p}T_{i}Q_{out}} - {C_{v}{T_{i}\left( {Q_{in} - Q_{out}} \right)}}} \right\rbrack}}} & \left( {{equation}\mspace{14mu} 15} \right)\end{matrix}$

Where:

M_(i)=mass of gas in chamber i;

Q_(ij) is the mass flow rate from chamber i to chamber j.

C_(ij) is the discharge coefficient of the valve between chamber i and j

A_(ij) is the area of the orifice of the valve between chamber i and j

ρ_(i) is the density of the gas in chamber i

Volume change effects are based on any changes in actual volume of thechamber in question. In one embodiment, this effect only applies tochamber 130-2, which can change size due to motion of membrane 127.

$\begin{matrix}{{{Volume}\mspace{14mu} {Change}\mspace{14mu} {Effects}} = {{\left( {\frac{C_{p}}{C_{v}} - 1} \right) \cdot \frac{T_{i}}{V_{i}}}\frac{{dV}_{i}}{dt}}} & \left( {{equation}\mspace{14mu} 16} \right)\end{matrix}$

Where:

V=volume

Cv=specific heat at constant volume

Cp=specific heat at constant pressure

The estimated temperature curves through the pumping and measurementcycles can be seen in FIGS. 5a, 5b , and 6.

In this method the control system has an estimated temperature for eachgas chamber that can be used in a modified ideal gas law volumecalculation that takes temperature into account:

$\begin{matrix}{V_{po} = {V_{com}\frac{\left( {\frac{P_{{com}\; 2}}{T_{{com}\; 2}} - \frac{P_{{com}\; 1}}{T_{{com}\; 1}}} \right)}{\left( {\frac{P_{{pc}\; 1}}{T_{{pc}\; 1}} - \frac{P_{{pc}\; 2}}{T_{{pc}\; 2}}} \right)}}} & \left( {{equation}\mspace{14mu} 17} \right)\end{matrix}$

Where:

-   -   V_(pc)=Unknown volume of the chamber 130-2 of diaphragm pump 130        (e.g., Left IPC)    -   V_(com)=the known volume of the chamber 150    -   P_(com1)=pressure P₃ from pressure sensor 135-3 of the chamber        150 at point [3]    -   P_(com2)=pressure P3 from pressure sensor 135-3 of the chamber        150 at point [5]    -   P_(pc1)=pressure P₅ from pressure sensor 135-5 of the chamber        130-2 at point [4]    -   P_(pc2)=pressure P₅ from pressure sensor 135-5 of the chamber        130-2 at point [5]    -   T_(com1)=estimated temperature of the chamber 150 at point [3A]    -   T_(com2)=estimated temperature of the chamber 150 at point [5A1]    -   P_(pc1)=estimated temperature of the chamber 130-2 at point [4A]    -   T_(pc2)=estimated temperature of the chamber 130-2 at point        [5A2]

As previously discussed, the volume of the chamber 130-1 can becalculated by subtracting the calculated VPC (e.g., volume of thepumping chamber 130-2) from the total volume of the diaphragm pump 130.The total volume of the diaphragm pump 130 is equal to the volume ofchamber 130-1 plus the volume of chamber 130-2 and is a known quantity.

In a further embodiment, the volume of chamber 130-1 is not calculated,and flow rate is calculated by simply taking the difference in volumebetween subsequent calculations of the volume of chamber 130-2. In otherwords, the change in volume of pump chamber 130-2 over time isindicative of a pumping flow rate and can be used as a basis tocalculate the flow rate. The controller 140 can be configured toprecisely determine a respective flow rate of delivering fluid fromchamber 130-one of diaphragm pump 130 based on the multiple measurementstaken at times C, D, E, etc., in FIG. 5b . The flow rate=(change involume of fluid in chamber 130-1)/(range of delivery time).

Using a temperature-corrected volume calculation (based on estimation ofgas temperatures as described herein) allows the system to have ameasure sequence that happens on the order of 80 milliseconds, ratherthan on the order of seconds while maintaining calculation accuracy.

FIG. 7 is an example block diagram of a computer device for implementingany of the operations as discussed herein according to embodimentsherein.

In one embodiment, fluid delivery system 100 includes a computer system750 to execute controller 140.

As shown, computer system 750 of the present example includes aninterconnect 711, a processor 713 (such as one or more processordevices, computer processor hardware, etc.), computer readable storagemedium 712 (such as hardware storage to store data), I/O interface 714,and communications interface 717.

Interconnect 711 provides connectivity amongst processor 713, computerreadable storage media 712, I/O interface 714, and communicationinterface 717.

I/O interface 714 provides connectivity to a repository 780 and, ifpresent, other devices such as a playback device, display screen, inputresource 792, a computer mouse, etc.

Computer readable storage medium 712 (such as a non-transitory hardwaremedium) can be any hardware storage resource or device such as memory,optical storage, hard drive, rotating disk, etc. In one embodiment, thecomputer readable storage medium 712 stores instructions executed byprocessor 713.

Communications interface 717 enables the computer system 750 andprocessor 713 to communicate over a resource such as network 190 toretrieve information from remote sources and communicate with othercomputers. I/O interface 714 enables processor 713 to retrieve storedinformation from repository 780.

As shown, computer readable storage media 712 is encoded with controllerapplication 140-1 (e.g., software, firmware, etc.) executed by processor713. Controller application 140-1 can be configured to includeinstructions to implement any of the operations as discussed herein.

During operation of one embodiment, processor 713 (e.g., computerprocessor hardware) accesses computer readable storage media 712 via theuse of interconnect 711 in order to launch, run, execute, interpret orotherwise perform the instructions in controller application 140-1stored on computer readable storage medium 712.

Execution of the controller application 140-1 produces processingfunctionality such as controller process 140-2 in processor 713. Inother words, the controller process 140-2 associated with processor 713represents one or more aspects of executing controller application 140-1within or upon the processor 713 in the computer system 750.

Those skilled in the art will understand that the computer system 750can include other processes and/or software and hardware components,such as an operating system that controls allocation and use of hardwareresources to execute controller application 140-1.

In accordance with different embodiments, note that computer system maybe any of various types of devices, including, but not limited to, awireless access point, a mobile computer, a personal computer system, awireless device, base station, phone device, desktop computer, laptop,notebook, netbook computer, mainframe computer system, handheldcomputer, workstation, network computer, application server, storagedevice, a consumer electronics device such as a camera, camcorder, settop box, mobile device, video game console, handheld video game device,a peripheral device such as a switch, modem, router, or in general anytype of computing or electronic device. In one non-limiting exampleembodiment, the computer system 850 resides in fluid delivery system100. However, note that computer system 850 may reside at any locationor can be included in any suitable resource in network environment 100to implement functionality as discussed herein.

Functionality supported by the different resources will now be discussedvia flowcharts in FIGS. 8, 9, and 10. Note that the steps in theflowcharts below can be executed in any suitable order.

FIG. 8 is a flowchart 800 illustrating an example method according toembodiments. Note that there will be some overlap with respect toconcepts as discussed above.

In processing block 810, the controller 140 controls magnitudes ofpressure in a first volume (such as chamber 150) and a second volume(such as chamber 130-2). The first volume is of a known magnitude (i.e.,size). The second volume is of an unknown magnitude (i.e., size).

In processing block 820, the controller 140 estimates a temperature ofgas in the first volume and a temperature of gas in the second volumebased on measurements of pressure in the first volume and measurementsof pressure in the second volume.

In processing block 830, the controller 140 calculates a magnitude ofthe second volume based on measured pressures of the gases and estimatedtemperatures of gases in the first volume and the second volume.

FIG. 9 is a flowchart 900 illustrating an example method according toembodiments. Note that there will be some overlap with respect toconcepts as discussed above.

In processing block 910, the controller 140 draws fluid into a chamberof a diaphragm pump 130.

In processing block 920, during a delivery phase, the controller 140applies pressure to the chamber 130-1. The applied pressure pumps thefluid in the chamber 130-1 to a target recipient 108.

In processing block 930, at multiple different times during the deliveryphase, the controller 140 temporarily discontinues application of thepressure to the chamber 130-2 to calculate how much of the fluid in thechamber 130-1 has been pumped to the target recipient 108.

FIG. 10 is a flowchart 1000 illustrating an example method according toembodiments. Note that there will be some overlap with respect toconcepts as discussed above.

In processing block 1010, the controller 140 controls magnitudes ofpressure in a first volume (such as chamber 150) and a second volume(such as chamber 130-2) to be dissimilar. The first volume is of knownmagnitude. The second volume is of unknown magnitude.

In processing block 1020, the controller 140 initiates opening a valve160-5 (while other valves are closed) between the first volume and thesecond volume to equalize a pressure in the first volume and the secondvolume.

In processing block 1030, the controller 140 estimates a temperature ofgas in the first volume and a temperature of gas in the second volumebased on a measured pressure in the first volume and measured pressureof the second volume.

In processing block 1040, the controller 140 calculates a magnitude ofthe second volume based on measured pressures of the gases and estimatedtemperatures of the gases in the first volume and the second volume.

As previously discussed, in one embodiment, a fluid delivery apparatusincludes controller hardware, a diaphragm pump, a positive displacementpump, and a fluid conduit extending between the diaphragm pump and thepositive displacement pump. During operation, and delivering fluid to adownstream recipient, the controller hardware draws fluid into a chamberof the diaphragm pump. The controller hardware applies pressure to thechamber of the diaphragm pump to output the fluid in the chamber of thediaphragm pump downstream through the fluid conduit to the positivedisplacement pump. A segment of the fluid conduit is an elasticallydeformable conduit driven by the positive displacement pump. Duringapplication of the pressure to the chamber and outputting the fluid inthe chamber downstream, the controller hardware activates the positivedisplacement pump to pump the fluid in the segment from the positivedisplacement pump to the downstream recipient.

More specifically, FIG. 11 is an example diagram of implementing adiaphragm pump and a positive displacement pump to deliver fluid to arespective recipient according to embodiments herein.

More specifically, in accordance with one or more embodiments, a fluiddelivery system (apparatus, device, etc.) includes controller 140(hardware and/or software), a diaphragm pump 130, a positivedisplacement pump 184 (such as a peristaltic fluid pump, rotary lobepump, progressive cavity pump, rotary gear pump, piston pump, diaphragmpump, screw pump, gear pump, hydraulic pump, rotary vane pump, ropepump, flexible impeller pump, etc.), and a fluid conduit (fluid conduit)extending between the diaphragm pump 130 through the positivedisplacement pump 184 to a recipient 108.

In one embodiment, the positive displacement pump is a non-pneumaticallycontrolled pump such as a peristaltic fluid pump, rotary lobe pump,progressive cavity pump, rotary gear pump, piston pump, screw pump, gearpump, rotary vane pump, rope pump, flexible impeller pump, etc.). Thediaphragm pump 130 is pneumatically (gas) driven and allows thecontroller to calculate flow rate as discussed herein.

In accordance with further embodiments, the positive displacement pump184 can be another diaphragm pump (i.e., a pneumatically driven pump).

During operation of delivering fluid to the downstream recipient 108,the controller 140 initially draws fluid into a chamber 130-1 of thediaphragm pump 130 (such as via negative gas pressure applied to chamber130-2).

As further described herein, subsequent to filling the chamber 130-1with fluid from fluid source 120-1, the controller 140 applies pressureto the chamber 130-1 of the diaphragm pump 130 to output the fluid inthe chamber 130-1 (of the diaphragm pump 130) downstream through thefluid conduit to the positive displacement pump 184 (such as viapositive gas pressure applied to chamber 130-2).

As shown, a segment 1110 of the fluid conduit of fluid delivery system100 is an elastically deformable conduit (of any suitable material suchas rubber, plastic, etc.) driven by the positive displacement pump 184.During application of the positive (gas) pressure to the chamber 130-1(via filling chamber 130-2 with more and more gas over time) andoutputting the fluid in the chamber 130-1 downstream to the positivedisplacement pump 184, the controller 140 activates the positivedisplacement pump 184 to pump the fluid disposed in a portion of thesegment 1110 downstream of the mechanical pump element 186-1 (such as aroller, peristaltic pump element, non-pneumatic pump element, or othersuitable element to movably compress segment 1110) along the fluidconduit to the downstream recipient 108.

Accordingly, in one embodiment, a diaphragm pump 130 delivers fluid tothe elastically deformable conduit (segment 1110); the controller 140controls the positive displacement pump 184 and corresponding mechanicalpump element 186-1 in a sweeping motion (in a downward direction in FIG.2) to deliver the fluid in the segment 1110 in a downstream direction torecipient 108.

More specifically, as shown, in one embodiment, the mechanical pumpelement 186-1 is in contact with and pinches or obstructs theelastically deformable conduit at position #1. Via the pinching, themechanical pump element 186-1 blocks a flow of fluid from the diaphragmpump 130 further downstream of position #1 into a portion of the segment1110 downstream of the mechanical pump element 186-1.

Sweeping physical contact of the mechanical pump element 186-1 to theelastically deformable conduit controllably conveys fluid in theelastically deformable conduit further downstream to the recipient 108.Accordingly, in one embodiment, the mechanical pump element 186-1performs multiple operations including: i) restricting (or holding back)a flow of the fluid received upstream of the mechanical pump element186-1 from the diaphragm pump 130 into the segment 1110 (elasticallydeformable conduit) as well as ii) via the positive displacement pump184, controlling delivery of fluid in the segment (elasticallydeformable conduit) downstream of the mechanical pump element 186-1 tothe recipient 108 (such as a person, animal, machine, etc.).

In accordance with further embodiments, a pressure (pressure #1) of thefluid upstream of the mechanical pump element 186-1 is different than apressure (pressure #2) of the fluid downstream of the mechanical pumpelement 186-1. More specifically, in one embodiment, during pumping offluid downstream from the diaphragm pump 130 to the positivedisplacement pump 184, a pressure #1 of the fluid in a first portion ofthe fluid conduit upstream of the mechanical pump element 186-1 (whichblocks a flow of the fluid via pinching or obstructing of the fluidconduit that conveys the fluid) is greater than a pressure (pressure #2)of fluid in a second portion of the fluid conduit downstream of themechanical pump element 186-1.

Conversely, in certain instances of pumping, the recipient 108 may applybackpressure on the fluid delivered through tube 105-3. In such aninstance, the pressure #1 of the fluid in a respective portion of thefluid conduit upstream of the mechanical pump element 186-1 (whichblocks a flow of the fluid via pinching/obstructing of the fluid conduitthat conveys the fluid) is less than a pressure (pressure #2) of fluidin a second portion of the fluid conduit downstream of the mechanicalpump element 186-1. For example, while the positive displacement pump184 pumps fluid, the recipient 108 may provide backpressure to receivingfluid from a respective outlet of fluid pathway through tube 105-3.

In accordance with another embodiment, the controller 140 of the fluiddelivery apparatus as described herein is further operable to: measure(in any suitable manner) a rate of fluid expelled from the chamber 130-1of the diaphragm pump 130 downstream to the segment of fluid conduitusing techniques as discussed in subsequent FIGS. 9-15 and text. In suchan instance, the controller 140 uses measured rate of expelled fluidfrom the chamber 130-1 over each of multiple measurement windows (shownas measurement D, measurement E, measurement F, measurement G,measurement age, in FIG. 10A; an example of a respective measurementwindow is shown in FIG. 11) to control a rate of moving the mechanicalpump element 186-1 to deliver the fluid to the recipient at a desiredflow rate. In such an embodiment, the diaphragm pump 130 serves as anaccurate way of measuring fluid delivered by the positive displacementpump 184 to the respective recipient 108.

Note that a rate of operating diaphragm pump 130 (pneumatic pump) andpositive displacement pump 184 can be synchronized such that thediaphragm pump 130 delivers fluid to the segment 1110 at a substantiallysimilar rate as the positive displacement pump 184 delivers fluid insegment 1110 downstream to the recipient 108.

As further discussed below, note that the fluid flow rate of fluidthrough the diaphragm pump 130 can be measured using conventionalalgorithms known in the art based on ideal gas laws. For example, in oneembodiment, the controller 140 is further operable to: cyclicallyreceive (draw), over each of multiple fill cycles, a quantum of thefluid from a disparately located fluid source container (such as fluidsource 120-1) into the chamber 130-1 of the diaphragm pump 130 at eachof multiple fill times. After each fill, as previously discussed, thecontroller 140 fills the chamber 130-2 with gas, which applies positivepressure to the chamber 130-1. As previously discussed, the membrane130-1 separates the fluid in chamber 130-1 from the gas in chamber130-2.

In one embodiment, fluid delivery system 100 includes valve 125-2 (suchas a fully OPEN or fully closed valve in this case); an OPEN/CLOSEDsetting of valve 125-2 is controlled by signal V9 generated bycontroller 140. Note that valve 125-2 is optional. That is, at least oneof the mechanical pump elements 186 can be configured to pinch orobstruct the segment 1110 and prevent a flow of fluid through segment1110 at any or all times.

FIG. 12 is an example diagram illustrating drawing of fluid from arespective fluid source into a chamber of a diaphragm pump according toembodiments herein.

As previously discussed, the controller 140 produces respective controlsignals to control states of the valves to either open or closedpositions. In one embodiment, while the valve 125-3 (a controllable fullopen or full closed valve in this embodiment) is open, valve 160-5 isopen, valve 160-1 is open, while valves 160-4 and 160-7 are closed, thecontroller 140 applies a negative pressure to the chamber 130-2 of thediaphragm pump 130. This evacuates gas from the chamber 130-2, causingthe membrane 127 to draw the fluid from the fluid source 120-1 (fluidcontainer) into chamber 130-1.

If desired, the controller 140 draws the fluid from the fluid source120-1 into the chamber 130-1 of the diaphragm pump 130 during acondition in which mechanical pump element 186-1 of the positivedisplacement pump 184 blocks a flow of any downstream fluid being pulledbackwards into the chamber 130-1. In other words, the mechanical pumpelement 186-1 acts as a valve in a closed position as shown in FIG. 3.Thus, instead of drawing fluid from further downstream of theelastically deformable conduit into the chamber 130-1, the applicationof the negative pressure to the chamber 130-2 causes the diaphragm pump130 to draw only the fluid from the upstream fluid source 120-1 into thechamber 130-1. As previously discussed, valve 125-2 in FIG. 2 isoptional.

FIG. 13 is an example diagram illustrating application of positivepressure to the chamber of the diaphragm pump to convey fluid to arespective downstream positive displacement pump according toembodiments herein.

As previously discussed, subsequent to drawing the fluid into thechamber 130-1 of the diaphragm pump 130, the controller 140 closes valve125-3 and valve 160-1 (via generation of respective control signals V8and V1); the controller 140 opens valve 160-5 and valve 160-4 (viageneration of respective control signals V5 and V4) to apply a positivegas pressure to the chamber 130-1 of the diaphragm pump 130 to deliverthe fluid in the chamber 130-1 downstream to the positive displacementpump 184.

As shown, during application of positive pressure to the fluid inchamber 130-1, the mechanical pump element 186-1 of the positivedisplacement pump 184 controls a rate at which fluid from the diaphragmpump 130 is allowed to flow downstream into the segment 1110. Aspreviously discussed, in addition to controlling an amount of fluidreceived in segment 1110 upstream of the mechanical pump element 186-1,the movement of the mechanical pump element 186-1 (in a downwarddirection) also controls the rate of delivering respective fluid in thesegment 1110 to the recipient 108.

As previously discussed, the controller can be configured tosynchronously operate rate of the diaphragm pump and positivedisplacement pump 184 such that the diaphragm pump 130 delivers fluid tothe segment 1110 at a substantially similar rate as the positivedisplacement pump 184 delivers fluid in segment 1110 downstream to therecipient 108.

FIG. 14 is an example diagram illustrating continued motion of amechanical pump element while receiving fluid from a diaphragm pumpaccording to embodiments herein.

As shown, the positive displacement pump 184 can be configured tocontinue to rotate over time about a respective axis (center ofmechanical pump elements 186) such that when the mechanical pump element186-1 reaches the end of the segment 1110, the next mechanical pumpelement 186-2 contacts the start location of segment 1110 to pinch orobstruct the segment 1110. This sets up the mechanical pump element186-1 of the positive displacement pump 184 to start location of segment1110. This starts a new cycle of sweeping the mechanical pump element186-2 along segment 1110 to deliver fluid to the respective recipient108. As previously discussed, in one embodiment, at least one of themechanical pump elements 186 always pinches, occludes, compresses,obstructs, etc., the segment 1110 to prevent backflow of fluid from thesegment 1110 to the diaphragm pump 130. Hence, valve 125-2 may not beneeded.

Note that the positive displacement pump 184 (a positive displacementpump) can be any type of peristaltic mechanism (rotary, linear, piston,etc.) as long as the downstream pump segment 1110 is never allowed toopen and allow free flow of fluid from the diaphragm pump 130 to therecipient 108. In other words, in one embodiment, the positivedisplacement pump or its corresponding elements (such as mechanical pumpelements 186-1, 186-2, etc.) can be configured to always occlude a flowof the fluid from the diaphragm pump 130 downstream to the recipient108. In such an instance, the positive displacement pump 184 constantlycontrols the flow of fluid to the recipient 108.

Note that the ratio of volume of fluid drawn into the chamber 130-1 maybe substantially the same or different than the volume of fluid insegment 1110. Accordingly, to empty all of the fluid stored in chamber130-1 may require: i) a single cycle of sweeping a mechanical pumpelement 186-1 along the segment 1110, ii) less than a single cycle ofsweeping a mechanical pump element 186-1 along the segment 1110, or iii)multiple cycles of sweeping mechanical pump elements along the segment1110.

Further, if desired, the positive displacement pump 184 can be operatedin a continuous manner to provide a continuous flow of fluid to therespective recipient 108 even though the controller 140 occasionally orperiodically initiates refilling of the chamber 130-1 during thecontinuous flow and movement of the mechanical pump elements 186.Alternatively, if desired, the controller 140 can be configured todiscontinue operation of the positive displacement pump 184 during acondition in which the chamber 130-1 is refilled with fluid from fluidsource 120-1.

In accordance with further embodiments, the controller 140 can beconfigured to stop (halt) movement of the positive displacement pump 184and corresponding one or more pump elements in contact with the segment1110. While the pump element is stopped, the controller 140 temporarilyadjusts the pressure applied to the chamber of the diaphragm pump tomeasure a respective portion of fluid remaining in the diaphragm pump ina manner as previously discussed. Thus, if desired, embodiments hereincan include pausing the positive displacement pumping mechanism todiscontinue flow of fluid from the positive displacement pump 184 to therecipient 108 during instances when the amount of fluid remaining in thechamber 130-1 is being measured in a respective sample window.

FIG. 15 is an example timing diagram illustrating multiple measurementwindows within each pump cycle according to embodiments herein.

In accordance with embodiments herein, during FILL #1, in a manner aspreviously discussed, the controller 140 applies negative pressure tothe chamber 130-2 and chamber 130-1 while valve 125-3 is open, and whilemechanical pump element 186-1 obstructs fluid flow and prevents backflowof fluid in segment 1110 to chamber 130-1. During FILL #2, a nextsuccessive time of filling chamber 130-1, the controller 140 appliesnegative pressure again to the chamber 130-2 while valve V8 is open, andwhile mechanical pump element 186-1 prevents backflow of fluid insegment 1110 to chamber 130-1.

At each of multiple measurement times between a first time of fillingFILL #1 and next filling FILL #2, the controller 140 temporarily adjustsapplication and a magnitude of the applied positive pressure to chamber130-1 in between windows (fluid drive windows FDW1, FDW2, FDW3, FDW4,etc.), which occur between fill times FILL #1 and FILL #2.

Interrupting application of pressure (while valve 125-3 controlled bysignal V8 is closed) can include temporarily changing the gas pressurefrom chamber 130-2 at each of multiple windows D1, E1, F1, G1, H1, etc.)to measure an amount of fluid remaining in chamber 130-1 at respectivetimes T61, T62, T63, T64, T65, etc.

The controller 140 uses the measured amount of fluid in the chamber130-1 at multiple sample times to derive a rate of delivering the fluidfrom the chamber 130-1 downstream to the segment 1110. For example, thechamber may hold 0.5 ml (milliliters) of fluid following FILL #1. Assumethat measurement in window FDW1 around time T61 indicates 0.5 ml in thechamber; measurement in window FDW2 around time T62 indicates 0.4 ml inthe chamber; measurement in window FDW3 around time T63 indicates 0.3 mlin the chamber; measurement in window FDW4 around time T64 indicates 0.2ml in the chamber; and so on. If the measurement windows are spacedapart by 4 seconds, then the controller 140 determines the rate of flowthrough the diaphragm pump 184 to be 0.3 ml/12 Seconds=90 millilitersper hour.

In accordance with more specific embodiments, the controller 140 furthercontrols the mechanical pump element 186-1 in contact with the segment1110 of fluid conduit to continuously move along a length of the segment1110 (such as even during FILL #1, FILL#2, etc.) to providecorresponding continuous flow of fluid from the segment 1110 to therecipient 108 in a respective delivery window.

As previously discussed, during each of multiple measurement windows(D1, E1, F1, G1, H1, for cycle #1, D2, E2, F2, G2, H2, for cycle #2,etc.) of interrupting application of the pressure within the deliverywindow, the controller 140 measures a respective portion of fluidremaining in the diaphragm pump 130. Note again that details ofmeasuring the amount of fluid in chamber 130-1 are discussed above inFIG. 10A as well as elsewhere throughout this specification.

The controller 140 utilizes the respective measured portions of fluidremaining in the diaphragm pump 130 as measured during the multiplemeasurement windows (D1, E1, F1, G1, H1, for cycle #1, D2, E2, F2, G2,H2, for cycle #2, etc.) to calculate a rate of fluid delivered by thepositive displacement pump 184 to the recipient 108. In the aboveexample, as previously discussed, the controller 140 determines the rateof flow through the diaphragm pump 184 to be 0.3 ml/12 Seconds=90milliliters per hour. This indicates that the rate of fluid delivered bythe positive displacement pump 184 is 90 milliliters per hour.Accordingly, the controller 140 utilizes the respective measuredportions of fluid remaining in the chamber 130-1 of the diaphragm pump130 as measured during the multiple measurement windows to calculate arate of fluid delivered by the positive displacement pump 184 to therecipient 108.

As further discussed below, the controller 140 can be configured to usethe measured flow rate to control operation of the positive displacementpump 184 such that the positive displacement pump 184 delivers fluid tothe recipient at a desired rate. For example, as further discussedbelow, if the flow rate of delivering fluids as indicated bymeasurements of the chamber 130-1 over time is less than a desired rate,the controller 140 increases a rate of moving the mechanical pumpelement 186-1 along segment 1110 to increase the rate of fluid flow torecipient 108. Conversely, if the flow rate of delivering fluids asindicated by measurements of the chamber 130-1 over time is greater thana desired rate, the controller 140 decreases a rate of moving themechanical pump element 186-1 along segment 1110 to decrease the rate offluid flow to recipient 108.

FIG. 16 is an example diagram illustrating control of a respectivepositive displacement pump based upon a calculated fluid flow rate offluid delivered by a respective diaphragm pump according to embodimentsherein.

As previously discussed, to provide precise fluid flow control over alarge possible range, the controller 140 measures a flow rate of fluiddelivered to the recipient 108 based upon measurements of a respectiveremaining portion of fluid in the chamber 130-1 over each of multiplesample times (such as measurement windows D1, E1, F1, G1, H1, for cycle#1; measurement windows D2, E2, F2, G2, H2, for cycle #2, etc.).

In one embodiment, as shown, the controller 140 includes diaphragm pumpinterface 1640. In a manner as previously discussed, the diaphragm pumpinterface 1640 is operable to measure a flow rate of the fluid expelledfrom the chamber 130-1 of the diaphragm pump 130 downstream to thesegment 1110 of the fluid conduit. As mentioned, techniques of measuringthe flow rate are discussed in FIGS. 9-15. During operation, thediaphragm pump interface 1640 produces signal 1630 indicating thecalculated fluid flow rate from diaphragm pump 130 downstream to thepositive displacement pump 184. The flow rate of fluid through thediaphragm pump 130 is generally (with slight variations over time) thesame flow rate that the positive displacement pump 184 delivers fluiddownstream to the recipient 108.

In accordance with further embodiments, the controller 140 utilizes themeasured flow rate of the fluid (as detected from measuring respectiveremaining portions of fluid in the chamber 130-1 of the diaphragm pump130 over multiple sample times T61, T62, T63, T64, etc.) to control(adjust) a sweep rate of moving the mechanical pump elements 186 alongthe segment 1110 of the fluid conduit to provide delivery of fluid fromthe positive displacement pump (and corresponding elastically deformableconduit) to the recipient 108 as specified by a desired flow ratesetting (such as a user selected rate).

For example, the difference logic 1620 produces a respective flow errorsignal 1660 indicating a difference between the calculated fluid flowrate as indicated by signal 1630 (as measured from the diaphragm pump130) and the target flow rate 1610.

If the measurement of fluid flowing through the diaphragm pump 130 (asmeasured over time) is greater than the desired flow rate setting,resulting in a positive flow error signal 1660, the positivedisplacement pump speed controller 1650 of the controller 140 decreasesa current rate of sweeping the mechanical pump element 186-1 alongsegment 1110. Conversely, if the measurement of the fluid flowingthrough the diaphragm pump 130 as detected by the controller 140 is lessthan the desired flow rate setting, resulting in a negative flow errorsignal 1660, the peristaltic pump speed controller 1650 of controller140 increases the rate of sweeping the mechanical pump element 186-1.

If desired, the controller 140 can be configured to monitor a magnitudeof pressure #1 to verify that there is no backup of fluid between thediaphragm pump 130 and the positive displacement pump 184.

In this manner, the controller 140 uses the flow error signal 1660 tocontrol the fluid flow to the target flow rate 1610. Accordingly, in oneembodiment, the measured rate of fluid flow through the diaphragm pump130 can be used as a basis to control the downstream peristaltic pump184 to provide very accurate fluid flow over a large range.

As further example, between time T61 and time T64, assume that thecontroller 140 is controlling the mechanical pump element 186-1 to movealong segment 1110 at a linear rate of 2.0 millimeters per second, whichresulted in a flow rate of 90 milliliters per hour as indicated above.If the target flow rate is 108 milliliters per hour, the error signal1660 indicates−18 milliliters per hour. To deliver fluid at anappropriate rate of 108 milliliters per hour, the controller 140increases a rate of moving the mechanical pump element 186-1 to a rateof 2.4 millimeters per second along segment 1110.

As previously discussed, the unique fluid delivery apparatus including adiaphragm pump 130 (to measure a fluid delivery rate) and a positivedisplacement pump 184 (to control physical pumping of fluid to arecipient 108) provides advantageous delivery of fluid in comparison toconventional techniques. For example, the fluid delivery apparatus andcorresponding methods as described herein provide one or more of thefollowing advantages over conventional techniques: i) fast start andstop time to reach desired delivery flow rate set point, ii) largedynamic range to control flow rates from 0.1 or lower to 1200 or higher,iii) flow rate control that is immune to inlet or outlet pressurechanges, iv) flow rate control that is immune to large variations influid properties (such as viscosity), and so on. Also, note thatvariation in size of the tubing due to manufacturing tolerances andvariation in contained volume in the tubing due to wear during operationcan cause variation in flow output.

Additionally, application of positive pressure to the diaphragm pump asdiscussed herein provides feeds fluid to a positive displacement pump,resulting in better flow continuity. Additionally, the diaphragm pump isoperable to draw fluid using negative pressure. In such an instance, thediaphragm pump can draw fluid from a container source disposed lower inelevation than the diaphragm pump.

FIG. 17 is an example diagram illustrating a method of delivering fluidto a respective recipient using a combination of a diaphragm pump and aperistaltic pump according to embodiments herein.

In processing operation 1710 of flowchart 1700, the controller 140(hardware and/or executed instructions of software) draws fluid fromfluid source 120-1 into chamber 130-1 of the diaphragm pump 130.

In processing operation 1720, the controller 140 applies pressure to thechamber 130-1 of the diaphragm pump 130 to output the fluid in thechamber 130-1 of the diaphragm pump 130 downstream through a fluidconduit to positive displacement pump 184.

In processing operation 1730, during application of the pressure tofluid in the chamber 130-1 and outputting the fluid from the chamberdownstream to the positive displacement pump 84, the controller 140activates operation of the positive displacement pump 184 to pump thefluid from the positive displacement pump 184 to a recipient 108.

Note again that techniques herein are well suited for use in fluiddelivery systems. However, it should be noted that embodiments hereinare not limited to use in such applications and that the techniquesdiscussed herein are well suited for other applications as well.

Based on the description set forth herein, numerous specific detailshave been set forth to provide a thorough understanding of claimedsubject matter. However, it will be understood by those skilled in theart that claimed subject matter may be practiced without these specificdetails. In other instances, methods, apparatuses, systems, etc., thatwould be known by one of ordinary skill have not been described indetail so as not to obscure claimed subject matter. Some portions of thedetailed description have been presented in terms of algorithms orsymbolic representations of operations on data bits or binary digitalsignals stored within a computing system memory, such as a computermemory. These algorithmic descriptions or representations are examplesof techniques used by those of ordinary skill in the data processingarts to convey the substance of their work to others skilled in the art.An algorithm as described herein, and generally, is considered to be aself-consistent sequence of operations or similar processing leading toa desired result. In this context, operations or processing involvephysical manipulation of physical quantities. Typically, although notnecessarily, such quantities may take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared orotherwise manipulated. It has been convenient at times, principally forreasons of common usage, to refer to such signals as bits, data, values,elements, symbols, characters, terms, numbers, numerals or the like. Itshould be understood, however, that all of these and similar terms areto be associated with appropriate physical quantities and are merelyconvenient labels. Unless specifically stated otherwise, as apparentfrom the following discussion, it is appreciated that throughout thisspecification discussions utilizing terms such as “processing,”“computing,” “calculating,” “determining” or the like refer to actionsor processes of a computing platform, such as a computer or a similarelectronic computing device, that manipulates or transforms datarepresented as physical electronic or magnetic quantities withinmemories, registers, or other information storage devices, transmissiondevices, or display devices of the computing platform.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of the presentapplication as defined by the appended claims. Such variations areintended to be covered by the scope of this present application. Assuch, the foregoing description of embodiments of the presentapplication is not intended to be limiting. Rather, any limitations tothe invention are presented in the following claims.

We claim:
 1. A method comprising: drawing fluid into a chamber of adiaphragm pump; applying a drive pressure to the chamber, the applieddrive pressure causing flow of the fluid out of the chamber in adownstream direction from the diaphragm pump through a conduit; in arespective flow measurement window of time, temporarily discontinuingapplication of the drive pressure to the chamber to calculate a portionof the fluid remaining in the chamber; and after the respective flowmeasurement window of time, resuming application of the drive pressureto the chamber to continue pumping the remaining portion of fluid in thechamber in the downstream direction through the conduit.
 2. The methodas in claim 1 further comprising: calculating amounts of fluid in thechamber at multiple different times during a delivery phase of expellingthe fluid in the chamber in the downstream direction through theconduit; and calculating a flow rate of delivering the fluid in thechamber through the conduit based on the calculated amounts of fluid inthe chamber at the multiple different times during the delivery phase.3. The method as in claim 2 further comprising: comparing the calculatedflow rate to a desired flow rate; receiving the fluid from the diaphragmpump at a peristaltic fluid pump, the peristaltic fluid pump operable toreceive the fluid form the diaphragm pump through the conduit; and inresponse to detecting a difference between the calculated flow rate flowrate of the fluid through the conduit and the desired flow rate isgreater than a threshold value, controlling the peristaltic fluid pumpdownstream of the diaphragm pump to deliver the fluid at a faster rate.4. The method as in claim 1, wherein applying the drive pressure to thechamber includes: applying a substantially constant pressure to thechamber to evacuate the fluid from the chamber into through the conduitthat conveys the fluid downstream to a target recipient.
 5. The methodas in claim 1, wherein application of the drive pressure to the chamberof the diaphragm pump outputs the fluid from the diaphragm pumpdownstream through the fluid conduit to a positive displacement fluidpump; and during application of the drive pressure to the chamber of thediaphragm pump and outputting of the fluid in the chamber downstream tothe positive displacement fluid pump, activating operation of thepositive displacement fluid pump to pump the fluid from the positivedisplacement fluid pump to a recipient.
 6. The method as in claim 1,wherein application of the drive pressure to the chamber of thediaphragm pump outputs the fluid in the chamber of the diaphragm pumpdownstream through the fluid conduit to an elastically deformablesegment of conduit driven by a peristaltic fluid pump; and duringapplication of the drive pressure to the chamber of the diaphragm pumpand outputting the fluid in the chamber downstream to the peristalticfluid pump, activating operation of the peristaltic fluid pump to pumpthe fluid in the elastically deformable segment from the peristalticfluid pump to a recipient.
 7. The method as in claim 6, wherein theperistaltic fluid pump includes a peristaltic pump element in sweepingphysical contact with the elastically deformable segment of the fluidconduit, the peristaltic pump element operable to restrict passage of aflow of the fluid received from the diaphragm pump through the segmentdownstream to the recipient.
 8. The method as in claim 1 furthercomprising: measuring a rate of fluid expelled from the chamber of thediaphragm pump downstream to an elastically deformable segment of fluidconduit; and controlling a rate of moving a peristaltic pump elementalong the elastically deformable segment to deliver the fluid from theelastically deformable segment to the recipient.
 9. The method as inclaim 1, wherein drawing the fluid into the chamber of the diaphragmpump includes receiving the fluid from a fluid container into thechamber of the diaphragm pump, the fluid container disparately locatedwith respect to the chamber of the diaphragm pump.
 10. The method as inclaim 1 further comprising: measuring a rate of the fluid being expelledfrom the chamber of the diaphragm pump downstream through the conduit toa downstream fluid pump, the downstream fluid pump blocking a flow ofthe fluid received from the diaphragm pump; and utilizing the measuredrate of fluid flow to control a rate of operating the downstream fluidpump to control delivery of fluid from the downstream fluid pump to arecipient as specified by a flow rate setting.
 11. The method as inclaim 1 further comprising: pumping the fluid in the chamber downstreamto a segment of conduit; controlling a pump element of a peristalticfluid pump in contact with the segment of conduit to continuously movealong a length of the segment to provide continuous flow of fluid fromthe segment to the recipient in a time window; and during each ofmultiple measurement windows in the time window, temporarilyinterrupting application of the drive pressure applied to the chamber ofthe diaphragm pump to measure a respective portion of fluid remaining inthe diaphragm pump.
 12. The method as in claim 1 further comprising:drawing the fluid from a fluid source into the chamber of the diaphragmpump during a condition in which a peristaltic pump element downstreamof the diaphragm pump blocks a reverse flow of the fluid in the conduitinto the chamber.
 13. A fluid delivery system comprising: a diaphragmpump; and a controller operable to: draw fluid into a chamber of adiaphragm pump; apply a drive pressure to the chamber, the applied drivepressure causing flow of the fluid out of the chamber in a downstreamdirection from the diaphragm pump through a conduit; in a respectiveflow measurement window of time, discontinue application of the drivepressure to the chamber to calculate a portion of the fluid remaining inthe chamber; and after the respective flow measurement window of time,resume application of the drive pressure to the chamber to continuepumping the remaining portion of fluid in the chamber in the downstreamdirection through the conduit.
 14. The fluid delivery system as in claim13, wherein the controller is operable to: calculate amounts of fluid inthe chamber at multiple different times during a delivery phase ofexpelling the fluid in the chamber in the downstream direction throughthe conduit; and calculate a flow rate of delivering the fluid in thechamber through the conduit based on the calculated amounts of fluid inthe chamber at the multiple different times during the delivery phase.15. The fluid delivery system as in claim 14, wherein the controller isoperable to: compare the calculated flow rate to a desired flow rate;receive the fluid from the diaphragm pump at a peristaltic fluid pump,the peristaltic fluid pump operable to receive the fluid form thediaphragm pump through the conduit; and in response to detecting adifference between the calculated flow rate flow rate of the fluidthrough the conduit and the desired flow rate is greater than athreshold value, control the peristaltic fluid pump downstream of thediaphragm pump to deliver the fluid at a faster rate.
 16. The fluiddelivery system as in claim 13, wherein the controller is operable to:apply a substantially constant pressure to the chamber to evacuate thefluid from the chamber into through the conduit that conveys the fluiddownstream to a target recipient.
 17. The fluid delivery system as inclaim 13, wherein application of the drive pressure to the chamber ofthe diaphragm pump outputs the fluid from the diaphragm pump downstreamthrough the fluid conduit to a positive displacement fluid pump, thecontroller further operable to: and during application of the drivepressure to the chamber of the diaphragm pump and outputting of thefluid in the chamber downstream to the positive displacement fluid pump,activating operation of the positive displacement fluid pump to pump thefluid from the positive displacement fluid pump to a recipient.
 18. Thefluid delivery system as in claim 13, wherein application of the drivepressure to the chamber of the diaphragm pump outputs the fluid in thechamber of the diaphragm pump downstream through the fluid conduit to anelastically deformable segment of conduit driven by a peristaltic fluidpump, the controller further operable to: and during application of thedrive pressure to the chamber of the diaphragm pump and outputting thefluid in the chamber downstream to the peristaltic fluid pump,activating operation of the peristaltic fluid pump to pump the fluid inthe elastically deformable segment from the peristaltic fluid pump to arecipient.
 19. The fluid delivery system as in claim 18, wherein theperistaltic fluid pump includes a peristaltic pump element in sweepingphysical contact with the elastically deformable segment of the fluidconduit, the peristaltic pump element restricting passage of a flow ofthe fluid received from the diaphragm pump through the segmentdownstream to the recipient.
 20. The fluid delivery system as in claim13, wherein the controller is operable to: measure a rate of fluidexpelled from the chamber of the diaphragm pump downstream to anelastically deformable segment of fluid conduit; and control a rate ofmoving a peristaltic pump element along the elastically deformablesegment to deliver the fluid from the elastically deformable segment tothe recipient.
 21. The fluid delivery system as in claim 13, wherein thediaphragm pump is operable to receive the fluid from a fluid container,the fluid container disparately located with respect to the chamber ofthe diaphragm pump.
 22. The fluid delivery system as in claim 13,wherein the controller is operable to: measure a rate of the fluid beingexpelled from the chamber of the diaphragm pump downstream through theconduit to a downstream fluid pump, the downstream fluid pump blocking aflow of the fluid received from the diaphragm pump; and utilize themeasured rate of fluid flow to control a rate of operating thedownstream fluid pump to control delivery of fluid from the downstreamfluid pump to a recipient as specified by a flow rate setting.
 23. Thefluid delivery system as in claim 13, wherein the controller is operableto: pump the fluid in the chamber downstream to a segment of conduit;control a pump element of a peristaltic fluid pump in contact with thesegment of conduit to continuously move along a length of the segment toprovide continuous flow of fluid from the segment to the recipient in atime window; and during each of multiple measurement windows in the timewindow, temporarily interrupt application of the drive pressure appliedto the chamber of the diaphragm pump to measure a respective portion offluid remaining in the diaphragm pump.
 24. The fluid delivery system asin claim 13, wherein the controller is operable to: draw the fluid froma fluid source into the chamber of the diaphragm pump during a conditionin which a peristaltic pump element downstream of the diaphragm pumpblocks a reverse flow of the fluid in the conduit into the chamber. 25.Computer-readable hardware storage having instructions stored thereon,the instructions, when carried out by computer processor hardware,causes the computer processor hardware to: draw fluid into a chamber ofa diaphragm pump; apply a drive pressure to the chamber, the applieddrive pressure causing flow of the fluid in the chamber in a downstreamdirection through a conduit; in a respective flow measurement window oftime, discontinue application of the drive pressure to the chamber tocalculate a portion of the fluid remaining in the chamber; and after therespective flow measurement window of time, resume application of thedrive pressure to the chamber to continue pumping the remaining portionof fluid in the chamber in the downstream direction through the conduit.